Graeme Puxty | CSIRO - Academia.edu (original) (raw)

Papers by Graeme Puxty

International Journal of Greenhouse Gas Control

A promising option to improve post combustion capture (PCC) is to use inorganic catalysts to acce... more A promising option to improve post combustion capture (PCC) is to use inorganic catalysts to accelerate the absorption process of CO2, in particular the reaction between CO2 and water to form carbonic acid. In this study, the efficiency of sulfate and vanadate on enhancing the hydration reaction of CO2 to form H2CO3 for PCC has been studied at 25 °C by stopped-flow spectrophotometry. The catalytic rate constants were determined to be 14.2(2) and 277(6) M−1 s−1 for sulfate and vanadate, respectively. Their application to PCC was further investigated by simulating the effect of these catalysts on the absorption process under PCC operating conditions. Vanadate was confirmed to have a greater efficiency toward CO2 hydration than sulfate and also a series of other inorganic catalysts reported earlier.

International Journal of Greenhouse Gas Control, 2015

ABSTRACT The Post Combustion Capture (PCC) process is currently the most applicable and effective... more ABSTRACT The Post Combustion Capture (PCC) process is currently the most applicable and effective approach to reduce emissions of CO2 from fossil fuel electricity generation. If the rate of CO2 hydration can be accelerated, the size of the absorber column can be reduced accordingly. Carbonic anhydrase type II (CAII), being one of the most active enzymes known for the reaction of CO2 with H2O, is a promising catalyst for CO2 absorption in aqueous solution for PCC application. In this study, the catalytic efficiencies of human (hCAII), wild type bovine (wtbCAII), and a series of wtbCAIIs (bCAM1–bCAM9) structurally modified in an attempt to improve thermal and salt stability were determined by stopped-flow spectrophotometry at 25 °C. wtbCAII and hCAII were found to have the highest activity for the hydration of CO2 while bCAM9 was the least efficient catalyst (catalytic rate constants of 1.198(6) × 108, 1.14(1) × 108 and 0.77(2) × 108 M−1s−1, respectively). The remaining mutants have similar catalytic efficiencies for CO2 hydration and fall in the range of 8.63(6) × 107–1.072(2) × 108 M−1s−1. In addition to these results, this study also verifies the analytical method developed for the study of enzymatic systems.

International Journal of Greenhouse Gas Control, 2015

To reduce CO2 emission into the atmosphere, particularly from coal-fired power stations, post com... more To reduce CO2 emission into the atmosphere, particularly from coal-fired power stations, post combustion capture (PCC) using amine-based solvents to chemically absorb CO2 has been extensively developed. From an infrastructure viewpoint, the faster the absorption of CO2, the smaller the absorber required. The use of catalysts for this process has been broadly studied. In this manuscript, a study of the catalytic efficiencies of inorganic oxoanions such as arsenite, arsenate, phosphite, phosphate, and borate is described. The kinetics of the accelerated CO2 absorption at 25 °C was investigated using stopped-flow spectrophotometry. The catalytic rate constants of these anions for the reaction of CO2 with H2O were determined to be 137.7(3), 30.3(7), 69(2), 32.7(9), and 13.66(7) M(-1)s(-1), respectively. A new mechanism for the catalytic reaction of oxoanions with CO2 has also been proposed. The applicability of these catalysts to PCC was further studied by simulation of the absorption process under PCC conditions using their experimental catalytic rate constants. Arsenite and phosphite were confirmed to be the best catalysts for CO2 capture. However, considering the toxicological effect of arsenic and the oxidative instability of phosphite, phosphate would be the most promising inorganic catalyst for PCC process from the series of inorganic oxoanions studied.

International Journal of Greenhouse Gas Control, 2015

ABSTRACT Piperazine (PZ) has been reported as an effective rate promoter in the aqueous ammonia-b... more ABSTRACT Piperazine (PZ) has been reported as an effective rate promoter in the aqueous ammonia-based solvent process for the post combustion capture (PCC) of CO2. However, the detailed promotion effect of PZ on CO2 absorption into partially loaded ammonia solutions and the mechanism of this process are still unclear. In an effort to determine the detailed promotion effect of PZ in aqueous ammonia-based solvents, overall mass transfer coefficients (KG) describing the absorption of CO2 into aqueous PZ/NH3 solutions were determined using a wetted-wall column apparatus at 25 °C. The effect of added PZ (from 0 to 0.5 M) on the mass transfer of CO2 into 3.0 M NH3 solutions over a range of pre-loaded CO2 concentrations of 0.9 M at 25 °C are reported in this work. The fast kinetic reactions of CO2(aq) with blended solutions containing PZ/NH3 were investigated using stopped-flow spectrophotometry at 25.0 °C. Analysis of the kinetic measurements using a chemical model which incorporates the complete reaction sets of the individual amines with CO2 (i.e., NH3-CO2-H2O and PZ-CO2-H2O) resulted in good agreement with the experimental data. The contribution distribution from each reactive species was calculated based on the proposed reaction scheme of the PZ-NH3-CO2-H2O system. Results show that both the PZ/PZH+ and /PZCO2H pathways make contributions to the promotion of CO2 absorption into PZ promoted aqueous NH3 solutions. Importantly, the reactive piperazine mono-carbamate species, /PZCO2H, which is present in the CO2-loaded mixtures of PZ/NH3, plays an important role in the promotion of CO2 absorption into CO2-loaded aqueous NH3 solutions. The mass transfer simulation results reveal that there are additional reactions occurring in the gas–liquid interface and gas phase due to the volatility of NH3, which requires further improvement on the simulation model.

International Journal of Greenhouse Gas Control, 2014

ABSTRACT The presence of SO2 in flue gas has a negative impact on typical CO2 capture processes u... more ABSTRACT The presence of SO2 in flue gas has a negative impact on typical CO2 capture processes utilising aqueous amines. For countries like Australia, that do not have flue gas desulphurisation, retrofitting such equipment to existing coal fired power stations is of the order of 100s of millions of dollars. In this work a new process configuration is described in which SO2is absorbed into a fraction of the absorbent used for CO2capture. SO2absorption is carried out in the bottom of the absorber column into a bleed stream from the bulk solvent, and a recycle flow allows the absorbent to be near saturation in SO2. This high concentration allows a number of low cost options for sulphur removal from the absorbent such as chemical treatment and precipitation, with predicted capital and operating costs in the range of 100s of thousands for a full scale plant. The principles underlying the concept, specifically kinetic selectivity of SO2absorptionover CO2and reactivity with amines, have been studied in the laboratory. Also a rate based model of an absorber column has been used to model the behaviour of SO2 from the application of the process concept to CSIRO’s CO2 capture pilot plant at Loy Yang power station. The laboratory and modelling results support both its feasibility and utility.

Chemical Engineering Journal, 2015

ABSTRACT Our recent studies have identified Benzylamine (BZA) as a promising candidate for CO2 ca... more ABSTRACT Our recent studies have identified Benzylamine (BZA) as a promising candidate for CO2 capture processes, however the formation of stable and insoluble BZA-carbamate salts in highly concentrated unblended BZA solutions, and at high CO2 loadings, severely restricts the working concentration of the unblended BZA solvent. Thus, BZA is ideally placed as a candidate for use in a formulated solvent to improve the overall amine concentration and CO2 loading which can be used. The current work focuses on the investigation of CO2 absorption into aqueous solutions of BZA as well as formulations of BZA incorporating MEA and AMP as the second amine components, respectively. Mass transfer/kinetic measurements using a wetted wall column (WWC) at 40oC have been performed for a series of unblended BZA solutions as well as a series of amine concentrations and ratios in the formulations. Overall mass transfer coefficients as a function of total CO2 loading in the solutions (0.0 – 0.4 moles CO2/ total mole amine in solution) have been determined for the unblended BZA solutions and formulations. CO2 absorption rates into unblended BZA solutions are significantly faster than in MEA solutions at similar concentrations and zero CO2 loading. The majority of the BZA formulations investigated here can be considered promising candidates for CO2 capture and possess larger or comparable mass transfer rates (up to 30% increase at low loadings) when compared to the corresponding unblended 5.0M and 6.0M MEA solutions under similar conditions. Formulations containing BZA and MEA demonstrated the fastest CO2 absorption rates overall due to the presence of two fast reacting amines, both of which can actively and directly contribute to the absorption of CO2.

Energy Procedia, 2014

The presence of SO 2 in flue gas has a negative impact on typical CO 2 capture processes utilisin... more The presence of SO 2 in flue gas has a negative impact on typical CO 2 capture processes utilising aqueous amines. For countries like Australia, that do not have flue gas desulfurisation, retrofitting such equipment to existing coal fired power stations is of the order of 100's of millions of dollars. In this work a new process configuration is described in which SO 2 is absorbed into a fraction of the absorbent used for CO 2 capture. SO 2 absorption is carried out in the bottom of the absorber column into a bleed stream from the bulk solvent, and a recycle flow allows the absorbent to be near saturation in SO 2 . This high concentration allows a number of low cost options for sulfur removal from the absorbent such as chemical treatment and precipitation. The principles underlying the concept, have been studied in the laboratory, and a rate based model of an absorber column has been used to model the SO 2 removal column section. The laboratory and modelling results support both the feasibility and utility of the process concept.

Energy Procedia, 2014

To date, a single mono-amine solvent with ideal properties for CO 2 capture processes is yet to b... more To date, a single mono-amine solvent with ideal properties for CO 2 capture processes is yet to be found. As a compromise, solvent formulations incorporating two or more individual amines into a single solvent blend have been proposed and are gaining momentum as next generation capture solvents. Recently we have identified benzylamine (BZA) for use as a CO 2 capture solvent. A significant drawback with BZA is the formation of stable carbamate salts at high CO 2 loadings which has severely limited the concentration of BZA which can be used. Thus, BZA is ideally placed as a candidate for use in formulations with other amines.

Energy Procedia, 2013

Most coals contain a certain amount of sulfur. Upon combustion most of the sulfur is initially ox... more Most coals contain a certain amount of sulfur. Upon combustion most of the sulfur is initially oxidized to SO 2 and later to SO 3 and sulfuric acid. If gaseous SO 2 enters the amine-based post combustion capture (PCC) plant it is immediately absorbed into the amine solution and transformed initially into sulfurous acid which dissociates into protons and the sulfite ion, SO 3 2-. The protons and sulfite remain in the amine solution and will accumulate over time. In this investigation we have studied the long term effect of dissolved SO 2 in MEA (monoethanolamine) solutions kept at 100°C by following the NMR spectrum of the solution. Additionally we have modeled the effect of increasing amounts of accumulated SO 2 on the cyclic capacity of the MEA solution as well as the reaction kinetics of dissolved CO 2 .

Energy Procedia, 2014

Formulated aqueous amine solvents incorporating two or more individual amines into a single blend... more Formulated aqueous amine solvents incorporating two or more individual amines into a single blended solvent are often suggested as alternative options to mono-amine solvents employed for CO 2 capture processes. Using software developed in Matlab and existing knowledge of chemical equilibria, investigations into the fundamental properties of formulated amine solvents and their interaction with CO 2 have been carried out. A simple solvent formulation containing equimolar amounts of monoethanolamine (MEA), Amine 1, and a sterically hindered / tertiary amine, Amine 2, has been investigated here. Specifically, the role of Amine 2 in the overall equilibrium behaviour of amine blends is discussed. Systematic variations of the protonation constants and reaction enthalpies of Amine 2 over a range of typical values has revealed that significant improvement can be made in terms of absorption capacity, cyclic capacity, and overall absorption enthalpy in the blends when compared to the standard 5.0M MEA solvent.

IOP Conference Series: Earth and Environmental Science, 2009

This article was submitted without an abstract, please refer to the full-text PDF file.

Chemical Engineering Journal, 2015

ABSTRACT Carbon dioxide (CO2) post combustion capture and storage is the most mature technology o... more ABSTRACT Carbon dioxide (CO2) post combustion capture and storage is the most mature technology option for the mitigation of CO2 emissions from fossil fuel electricity generation. Typically CO2 separation at low pressure is achieved by reactive chemical absorption using aqueous amines. In this work benzylamine (BZA) has been assessed in terms of the chemical and physical properties relevant for its application as an aqueous amine CO2 absorbent. BZA was found to have similar reaction kinetics with CO2 to monoethanolamine (MEA) (kcarb = 7600 M�1 s�1 at 35 �C and Ea = 38 kJ mol�1) and similar carbamate stability but with a �40% larger enthalpy of protonation. It was also found to be less corrosive and have lower viscosity and heat capacity. Significant performance gains relative to MEA 30 wt% were predicted by using BZA in a formulation with either MEA or 2-amino-2-methyl-1-proponal (AMP) with predicted reductions in reboiler duty up to 13%, improvements in mass transfer up to 20% and low corrosion potential.

Energy Procedia, 2009

... Interactions between Amine and Carbonate Species in Aqueous Solution - Kinetics and Thermodyn... more ... Interactions between Amine and Carbonate Species in Aqueous Solution - Kinetics and Thermodynamics Nichola McCann a , Duong Phan a , Moetaz Attalla b , Graeme Puxty b , Debra Fernandes a ... (10) Kumar, PS; Hogendoorn, JA; Timmer, SJ; Feron, PHM; Versteeg, GF Ind. ...

Energy Procedia, 2014

The energy penalty of post-combustion capture of CO 2 (PCC) presents a major hurdle in the applic... more The energy penalty of post-combustion capture of CO 2 (PCC) presents a major hurdle in the application of this technology for CO 2 -emission reduction and CO 2 utilisation in China. Huaneng CERI and CSIRO have been collaborating since 2008 with the aim of developing low-cost, energy-efficient and environmentally benign aminebased PCC processes. This paper provides an update on recent advancements in this area which has focused on:

Energy Procedia, 2011

The most common method of CO2 capture is the absorption of CO2 into a falling thin film of an aqu... more The most common method of CO2 capture is the absorption of CO2 into a falling thin film of an aqueous amine solution. Modelling of mass transfer during CO2 absorption is an important way to gain insight and understanding about the underlying processes that are occurring. In this work a new software tool has been used to model CO2 absorption into

Energy Procedia, 2009

Carbon dioxide (CO2) is now recognised as the greenhouse gas contributing most to global warming ... more Carbon dioxide (CO2) is now recognised as the greenhouse gas contributing most to global warming and implicated in climate change model predictions. Electricity generation from fossil fuel combustion is a major source of CO2 emissions both internationally (32% of total CO2 emissions) and nationally (50% of total CO2 emissions). To effectively reduce CO2 emissions in the short to medium term

Quantitative 13C NMR spectroscopy was used to study the reaction of CO2 with aqueous amines. A nu... more Quantitative 13C NMR spectroscopy was used to study the reaction of CO2 with aqueous amines. A number of structurally different amines were studied using this method to investigate their CO2 absorption and desorption under different reaction conditions. The results demonstrate that this method is easily applicable to both CO2 absorption and desorption with aqueous amines solutions. The study showed that

BioInorganic Reaction Mechanisms, 2003

ABSTRACT Kinetic what-if simulations can be important for both the optimisation of an industrial ... more ABSTRACT Kinetic what-if simulations can be important for both the optimisation of an industrial process as well as the design of future experiments in the evolving process of a detailed kinetic analysis on laboratory scale. From our viewpoint as coordination chemists we present SIMKIN, a tool for an easy intuitive and fast simulation of chemical kinetics. As one of the key features, an intelligent model parser translates conventional chemical equations consisting of virtually any reaction steps including feedbacks into the rate law. The corresponding differential equations are then solved by standard routines for numerical integration, and the concentration profiles of the involved species plotted versus the reaction time. By means of selected kinetic examples of increasing complexity taken from coordination chemistry we demonstrate the capabilities and versatility of the program. A MATLAB® version with a complete graphical user interface can be requested from the authors free of charge.

Chemical Engineering Science, 2015

ABSTRACT Presently monoethanolamine (MEA) remains the industrial standard solvent for CO2 capture... more ABSTRACT Presently monoethanolamine (MEA) remains the industrial standard solvent for CO2 capture processes. Operating issues relating to corrosion and degradation of MEA at high temperatures and concentrations, and in the presence of oxygen, in a traditional PCC process, have introduced the requisite for higher quality and costly stainless steels in the construction of capture equipment and the use of oxygen scavengers and corrosion inhibitors. While capture processes employing MEA have improved significantly in recent times there is a continued attraction towards alternative solvents systems which offer even more improvements. This movement includes aqueous amine blends which are gaining momentum as new generation solvents for CO2 capture processes. Given the exhaustive array of amines available to date endless opportunities exist to tune and tailor a solvent to deliver specific performance and physical properties in line with a desired capture process. The current work is focussed on the rationalisation of CO2 absorption behaviour in a series of aqueous amine blends incorporating monoethanolamine, N,N-dimethylethanolamine (DMEA), N,N-diethylethanolamine (DEEA) and 2-amino-2-methyl-1-propanol (AMP) as solvent components. Mass transfer/kinetic measurements have been performed using a wetted wall column (WWC) contactor at 40 °C for a series of blends in which the blend properties including amine concentration, blend ratio, and CO2 loadings from 0.0–0.4 (moles CO2/total moles amine) were systematically varied and assessed. Equilibrium CO2 solubility in each of the blends has been estimated using a software tool developed in Matlab for the prediction of vapour liquid equilibrium using a combination of the known chemical equilibrium reactions and constants for the individual amine components which have been combined into a blend.

The Journal of Physical Chemistry C, 2013

ABSTRACT An amine-grafted solid sorbent is a promising alternative to aqueous amine scrubbing for... more ABSTRACT An amine-grafted solid sorbent is a promising alternative to aqueous amine scrubbing for removing CO2 from the flue gas of coal power plants. In this study, phosphonic and carboxylic acids have been investigated as alternative anchor groups to trimethoxysilanes to synthesize amine-functionalized TiO2-based sorbents. Several supports, namely, mesoporous TiO2 beads, TiO2 nanoparticles (Degussa P25), and TiO2/ZrO2 composite beads, and a range of amines (1, 2, and 3 carbon-chain primary amine) have been assessed for CO2 adsorption at 30 °C and up to 101 kPa CO2. As a general trend, CO2 adsorption capacity increased with the carbon-chain length of the amine. Finally, materials functionalized with amino acids, l-glutamine or l-arginine, were investigated; the latter showed the highest CO2 adsorption capacity (0.4 mmol/g at 30 °C and 20 kPa CO2) due to the higher pKa (12.10) of one of the amino groups.

International Journal of Greenhouse Gas Control

A promising option to improve post combustion capture (PCC) is to use inorganic catalysts to acce... more A promising option to improve post combustion capture (PCC) is to use inorganic catalysts to accelerate the absorption process of CO2, in particular the reaction between CO2 and water to form carbonic acid. In this study, the efficiency of sulfate and vanadate on enhancing the hydration reaction of CO2 to form H2CO3 for PCC has been studied at 25 °C by stopped-flow spectrophotometry. The catalytic rate constants were determined to be 14.2(2) and 277(6) M−1 s−1 for sulfate and vanadate, respectively. Their application to PCC was further investigated by simulating the effect of these catalysts on the absorption process under PCC operating conditions. Vanadate was confirmed to have a greater efficiency toward CO2 hydration than sulfate and also a series of other inorganic catalysts reported earlier.

International Journal of Greenhouse Gas Control, 2015

ABSTRACT The Post Combustion Capture (PCC) process is currently the most applicable and effective... more ABSTRACT The Post Combustion Capture (PCC) process is currently the most applicable and effective approach to reduce emissions of CO2 from fossil fuel electricity generation. If the rate of CO2 hydration can be accelerated, the size of the absorber column can be reduced accordingly. Carbonic anhydrase type II (CAII), being one of the most active enzymes known for the reaction of CO2 with H2O, is a promising catalyst for CO2 absorption in aqueous solution for PCC application. In this study, the catalytic efficiencies of human (hCAII), wild type bovine (wtbCAII), and a series of wtbCAIIs (bCAM1–bCAM9) structurally modified in an attempt to improve thermal and salt stability were determined by stopped-flow spectrophotometry at 25 °C. wtbCAII and hCAII were found to have the highest activity for the hydration of CO2 while bCAM9 was the least efficient catalyst (catalytic rate constants of 1.198(6) × 108, 1.14(1) × 108 and 0.77(2) × 108 M−1s−1, respectively). The remaining mutants have similar catalytic efficiencies for CO2 hydration and fall in the range of 8.63(6) × 107–1.072(2) × 108 M−1s−1. In addition to these results, this study also verifies the analytical method developed for the study of enzymatic systems.

International Journal of Greenhouse Gas Control, 2015

To reduce CO2 emission into the atmosphere, particularly from coal-fired power stations, post com... more To reduce CO2 emission into the atmosphere, particularly from coal-fired power stations, post combustion capture (PCC) using amine-based solvents to chemically absorb CO2 has been extensively developed. From an infrastructure viewpoint, the faster the absorption of CO2, the smaller the absorber required. The use of catalysts for this process has been broadly studied. In this manuscript, a study of the catalytic efficiencies of inorganic oxoanions such as arsenite, arsenate, phosphite, phosphate, and borate is described. The kinetics of the accelerated CO2 absorption at 25 °C was investigated using stopped-flow spectrophotometry. The catalytic rate constants of these anions for the reaction of CO2 with H2O were determined to be 137.7(3), 30.3(7), 69(2), 32.7(9), and 13.66(7) M(-1)s(-1), respectively. A new mechanism for the catalytic reaction of oxoanions with CO2 has also been proposed. The applicability of these catalysts to PCC was further studied by simulation of the absorption process under PCC conditions using their experimental catalytic rate constants. Arsenite and phosphite were confirmed to be the best catalysts for CO2 capture. However, considering the toxicological effect of arsenic and the oxidative instability of phosphite, phosphate would be the most promising inorganic catalyst for PCC process from the series of inorganic oxoanions studied.

International Journal of Greenhouse Gas Control, 2015

ABSTRACT Piperazine (PZ) has been reported as an effective rate promoter in the aqueous ammonia-b... more ABSTRACT Piperazine (PZ) has been reported as an effective rate promoter in the aqueous ammonia-based solvent process for the post combustion capture (PCC) of CO2. However, the detailed promotion effect of PZ on CO2 absorption into partially loaded ammonia solutions and the mechanism of this process are still unclear. In an effort to determine the detailed promotion effect of PZ in aqueous ammonia-based solvents, overall mass transfer coefficients (KG) describing the absorption of CO2 into aqueous PZ/NH3 solutions were determined using a wetted-wall column apparatus at 25 °C. The effect of added PZ (from 0 to 0.5 M) on the mass transfer of CO2 into 3.0 M NH3 solutions over a range of pre-loaded CO2 concentrations of 0.9 M at 25 °C are reported in this work. The fast kinetic reactions of CO2(aq) with blended solutions containing PZ/NH3 were investigated using stopped-flow spectrophotometry at 25.0 °C. Analysis of the kinetic measurements using a chemical model which incorporates the complete reaction sets of the individual amines with CO2 (i.e., NH3-CO2-H2O and PZ-CO2-H2O) resulted in good agreement with the experimental data. The contribution distribution from each reactive species was calculated based on the proposed reaction scheme of the PZ-NH3-CO2-H2O system. Results show that both the PZ/PZH+ and /PZCO2H pathways make contributions to the promotion of CO2 absorption into PZ promoted aqueous NH3 solutions. Importantly, the reactive piperazine mono-carbamate species, /PZCO2H, which is present in the CO2-loaded mixtures of PZ/NH3, plays an important role in the promotion of CO2 absorption into CO2-loaded aqueous NH3 solutions. The mass transfer simulation results reveal that there are additional reactions occurring in the gas–liquid interface and gas phase due to the volatility of NH3, which requires further improvement on the simulation model.

International Journal of Greenhouse Gas Control, 2014

ABSTRACT The presence of SO2 in flue gas has a negative impact on typical CO2 capture processes u... more ABSTRACT The presence of SO2 in flue gas has a negative impact on typical CO2 capture processes utilising aqueous amines. For countries like Australia, that do not have flue gas desulphurisation, retrofitting such equipment to existing coal fired power stations is of the order of 100s of millions of dollars. In this work a new process configuration is described in which SO2is absorbed into a fraction of the absorbent used for CO2capture. SO2absorption is carried out in the bottom of the absorber column into a bleed stream from the bulk solvent, and a recycle flow allows the absorbent to be near saturation in SO2. This high concentration allows a number of low cost options for sulphur removal from the absorbent such as chemical treatment and precipitation, with predicted capital and operating costs in the range of 100s of thousands for a full scale plant. The principles underlying the concept, specifically kinetic selectivity of SO2absorptionover CO2and reactivity with amines, have been studied in the laboratory. Also a rate based model of an absorber column has been used to model the behaviour of SO2 from the application of the process concept to CSIRO’s CO2 capture pilot plant at Loy Yang power station. The laboratory and modelling results support both its feasibility and utility.

Chemical Engineering Journal, 2015

ABSTRACT Our recent studies have identified Benzylamine (BZA) as a promising candidate for CO2 ca... more ABSTRACT Our recent studies have identified Benzylamine (BZA) as a promising candidate for CO2 capture processes, however the formation of stable and insoluble BZA-carbamate salts in highly concentrated unblended BZA solutions, and at high CO2 loadings, severely restricts the working concentration of the unblended BZA solvent. Thus, BZA is ideally placed as a candidate for use in a formulated solvent to improve the overall amine concentration and CO2 loading which can be used. The current work focuses on the investigation of CO2 absorption into aqueous solutions of BZA as well as formulations of BZA incorporating MEA and AMP as the second amine components, respectively. Mass transfer/kinetic measurements using a wetted wall column (WWC) at 40oC have been performed for a series of unblended BZA solutions as well as a series of amine concentrations and ratios in the formulations. Overall mass transfer coefficients as a function of total CO2 loading in the solutions (0.0 – 0.4 moles CO2/ total mole amine in solution) have been determined for the unblended BZA solutions and formulations. CO2 absorption rates into unblended BZA solutions are significantly faster than in MEA solutions at similar concentrations and zero CO2 loading. The majority of the BZA formulations investigated here can be considered promising candidates for CO2 capture and possess larger or comparable mass transfer rates (up to 30% increase at low loadings) when compared to the corresponding unblended 5.0M and 6.0M MEA solutions under similar conditions. Formulations containing BZA and MEA demonstrated the fastest CO2 absorption rates overall due to the presence of two fast reacting amines, both of which can actively and directly contribute to the absorption of CO2.

Energy Procedia, 2014

The presence of SO 2 in flue gas has a negative impact on typical CO 2 capture processes utilisin... more The presence of SO 2 in flue gas has a negative impact on typical CO 2 capture processes utilising aqueous amines. For countries like Australia, that do not have flue gas desulfurisation, retrofitting such equipment to existing coal fired power stations is of the order of 100's of millions of dollars. In this work a new process configuration is described in which SO 2 is absorbed into a fraction of the absorbent used for CO 2 capture. SO 2 absorption is carried out in the bottom of the absorber column into a bleed stream from the bulk solvent, and a recycle flow allows the absorbent to be near saturation in SO 2 . This high concentration allows a number of low cost options for sulfur removal from the absorbent such as chemical treatment and precipitation. The principles underlying the concept, have been studied in the laboratory, and a rate based model of an absorber column has been used to model the SO 2 removal column section. The laboratory and modelling results support both the feasibility and utility of the process concept.

Energy Procedia, 2014

To date, a single mono-amine solvent with ideal properties for CO 2 capture processes is yet to b... more To date, a single mono-amine solvent with ideal properties for CO 2 capture processes is yet to be found. As a compromise, solvent formulations incorporating two or more individual amines into a single solvent blend have been proposed and are gaining momentum as next generation capture solvents. Recently we have identified benzylamine (BZA) for use as a CO 2 capture solvent. A significant drawback with BZA is the formation of stable carbamate salts at high CO 2 loadings which has severely limited the concentration of BZA which can be used. Thus, BZA is ideally placed as a candidate for use in formulations with other amines.

Energy Procedia, 2013

Most coals contain a certain amount of sulfur. Upon combustion most of the sulfur is initially ox... more Most coals contain a certain amount of sulfur. Upon combustion most of the sulfur is initially oxidized to SO 2 and later to SO 3 and sulfuric acid. If gaseous SO 2 enters the amine-based post combustion capture (PCC) plant it is immediately absorbed into the amine solution and transformed initially into sulfurous acid which dissociates into protons and the sulfite ion, SO 3 2-. The protons and sulfite remain in the amine solution and will accumulate over time. In this investigation we have studied the long term effect of dissolved SO 2 in MEA (monoethanolamine) solutions kept at 100°C by following the NMR spectrum of the solution. Additionally we have modeled the effect of increasing amounts of accumulated SO 2 on the cyclic capacity of the MEA solution as well as the reaction kinetics of dissolved CO 2 .

Energy Procedia, 2014

Formulated aqueous amine solvents incorporating two or more individual amines into a single blend... more Formulated aqueous amine solvents incorporating two or more individual amines into a single blended solvent are often suggested as alternative options to mono-amine solvents employed for CO 2 capture processes. Using software developed in Matlab and existing knowledge of chemical equilibria, investigations into the fundamental properties of formulated amine solvents and their interaction with CO 2 have been carried out. A simple solvent formulation containing equimolar amounts of monoethanolamine (MEA), Amine 1, and a sterically hindered / tertiary amine, Amine 2, has been investigated here. Specifically, the role of Amine 2 in the overall equilibrium behaviour of amine blends is discussed. Systematic variations of the protonation constants and reaction enthalpies of Amine 2 over a range of typical values has revealed that significant improvement can be made in terms of absorption capacity, cyclic capacity, and overall absorption enthalpy in the blends when compared to the standard 5.0M MEA solvent.

IOP Conference Series: Earth and Environmental Science, 2009

This article was submitted without an abstract, please refer to the full-text PDF file.

Chemical Engineering Journal, 2015

ABSTRACT Carbon dioxide (CO2) post combustion capture and storage is the most mature technology o... more ABSTRACT Carbon dioxide (CO2) post combustion capture and storage is the most mature technology option for the mitigation of CO2 emissions from fossil fuel electricity generation. Typically CO2 separation at low pressure is achieved by reactive chemical absorption using aqueous amines. In this work benzylamine (BZA) has been assessed in terms of the chemical and physical properties relevant for its application as an aqueous amine CO2 absorbent. BZA was found to have similar reaction kinetics with CO2 to monoethanolamine (MEA) (kcarb = 7600 M�1 s�1 at 35 �C and Ea = 38 kJ mol�1) and similar carbamate stability but with a �40% larger enthalpy of protonation. It was also found to be less corrosive and have lower viscosity and heat capacity. Significant performance gains relative to MEA 30 wt% were predicted by using BZA in a formulation with either MEA or 2-amino-2-methyl-1-proponal (AMP) with predicted reductions in reboiler duty up to 13%, improvements in mass transfer up to 20% and low corrosion potential.

Energy Procedia, 2009

... Interactions between Amine and Carbonate Species in Aqueous Solution - Kinetics and Thermodyn... more ... Interactions between Amine and Carbonate Species in Aqueous Solution - Kinetics and Thermodynamics Nichola McCann a , Duong Phan a , Moetaz Attalla b , Graeme Puxty b , Debra Fernandes a ... (10) Kumar, PS; Hogendoorn, JA; Timmer, SJ; Feron, PHM; Versteeg, GF Ind. ...

Energy Procedia, 2014

The energy penalty of post-combustion capture of CO 2 (PCC) presents a major hurdle in the applic... more The energy penalty of post-combustion capture of CO 2 (PCC) presents a major hurdle in the application of this technology for CO 2 -emission reduction and CO 2 utilisation in China. Huaneng CERI and CSIRO have been collaborating since 2008 with the aim of developing low-cost, energy-efficient and environmentally benign aminebased PCC processes. This paper provides an update on recent advancements in this area which has focused on:

Energy Procedia, 2011

The most common method of CO2 capture is the absorption of CO2 into a falling thin film of an aqu... more The most common method of CO2 capture is the absorption of CO2 into a falling thin film of an aqueous amine solution. Modelling of mass transfer during CO2 absorption is an important way to gain insight and understanding about the underlying processes that are occurring. In this work a new software tool has been used to model CO2 absorption into

Energy Procedia, 2009

Carbon dioxide (CO2) is now recognised as the greenhouse gas contributing most to global warming ... more Carbon dioxide (CO2) is now recognised as the greenhouse gas contributing most to global warming and implicated in climate change model predictions. Electricity generation from fossil fuel combustion is a major source of CO2 emissions both internationally (32% of total CO2 emissions) and nationally (50% of total CO2 emissions). To effectively reduce CO2 emissions in the short to medium term

Quantitative 13C NMR spectroscopy was used to study the reaction of CO2 with aqueous amines. A nu... more Quantitative 13C NMR spectroscopy was used to study the reaction of CO2 with aqueous amines. A number of structurally different amines were studied using this method to investigate their CO2 absorption and desorption under different reaction conditions. The results demonstrate that this method is easily applicable to both CO2 absorption and desorption with aqueous amines solutions. The study showed that

BioInorganic Reaction Mechanisms, 2003

ABSTRACT Kinetic what-if simulations can be important for both the optimisation of an industrial ... more ABSTRACT Kinetic what-if simulations can be important for both the optimisation of an industrial process as well as the design of future experiments in the evolving process of a detailed kinetic analysis on laboratory scale. From our viewpoint as coordination chemists we present SIMKIN, a tool for an easy intuitive and fast simulation of chemical kinetics. As one of the key features, an intelligent model parser translates conventional chemical equations consisting of virtually any reaction steps including feedbacks into the rate law. The corresponding differential equations are then solved by standard routines for numerical integration, and the concentration profiles of the involved species plotted versus the reaction time. By means of selected kinetic examples of increasing complexity taken from coordination chemistry we demonstrate the capabilities and versatility of the program. A MATLAB® version with a complete graphical user interface can be requested from the authors free of charge.

Chemical Engineering Science, 2015

ABSTRACT Presently monoethanolamine (MEA) remains the industrial standard solvent for CO2 capture... more ABSTRACT Presently monoethanolamine (MEA) remains the industrial standard solvent for CO2 capture processes. Operating issues relating to corrosion and degradation of MEA at high temperatures and concentrations, and in the presence of oxygen, in a traditional PCC process, have introduced the requisite for higher quality and costly stainless steels in the construction of capture equipment and the use of oxygen scavengers and corrosion inhibitors. While capture processes employing MEA have improved significantly in recent times there is a continued attraction towards alternative solvents systems which offer even more improvements. This movement includes aqueous amine blends which are gaining momentum as new generation solvents for CO2 capture processes. Given the exhaustive array of amines available to date endless opportunities exist to tune and tailor a solvent to deliver specific performance and physical properties in line with a desired capture process. The current work is focussed on the rationalisation of CO2 absorption behaviour in a series of aqueous amine blends incorporating monoethanolamine, N,N-dimethylethanolamine (DMEA), N,N-diethylethanolamine (DEEA) and 2-amino-2-methyl-1-propanol (AMP) as solvent components. Mass transfer/kinetic measurements have been performed using a wetted wall column (WWC) contactor at 40 °C for a series of blends in which the blend properties including amine concentration, blend ratio, and CO2 loadings from 0.0–0.4 (moles CO2/total moles amine) were systematically varied and assessed. Equilibrium CO2 solubility in each of the blends has been estimated using a software tool developed in Matlab for the prediction of vapour liquid equilibrium using a combination of the known chemical equilibrium reactions and constants for the individual amine components which have been combined into a blend.

The Journal of Physical Chemistry C, 2013

ABSTRACT An amine-grafted solid sorbent is a promising alternative to aqueous amine scrubbing for... more ABSTRACT An amine-grafted solid sorbent is a promising alternative to aqueous amine scrubbing for removing CO2 from the flue gas of coal power plants. In this study, phosphonic and carboxylic acids have been investigated as alternative anchor groups to trimethoxysilanes to synthesize amine-functionalized TiO2-based sorbents. Several supports, namely, mesoporous TiO2 beads, TiO2 nanoparticles (Degussa P25), and TiO2/ZrO2 composite beads, and a range of amines (1, 2, and 3 carbon-chain primary amine) have been assessed for CO2 adsorption at 30 °C and up to 101 kPa CO2. As a general trend, CO2 adsorption capacity increased with the carbon-chain length of the amine. Finally, materials functionalized with amino acids, l-glutamine or l-arginine, were investigated; the latter showed the highest CO2 adsorption capacity (0.4 mmol/g at 30 °C and 20 kPa CO2) due to the higher pKa (12.10) of one of the amino groups.