Hans Geerlings | Delft University of Technology (original) (raw)

Papers by Hans Geerlings

Catal. Sci. Technol., 2015

We demonstrate that the kinetics of the Sabatier reaction catalysed by sorption catalysts depends... more We demonstrate that the kinetics of the Sabatier reaction catalysed by sorption catalysts depends on the nanostructure of the catalyst–sorbent system, and in particular on the shape selectivity of the zeolite sorbent.

Energy Procedia, 2011

Two experimental modes of operation, a sequence of batch and a continuous one, have demonstrated ... more Two experimental modes of operation, a sequence of batch and a continuous one, have demonstrated the technical feasibility of Shell’s proposed slurry-based direct flue gas mineralization concept on the basis of activated serpentine. The base case mineralization concept can be simplified yielding a variety of product forms and significantly reduced CO2 abatement costs. Combined with a positive first assessment of

Physical Chemistry Chemical Physics

Neutron imaging reveals the amount of hydrogen intercalated into technical methanol catalysts as ... more Neutron imaging reveals the amount of hydrogen intercalated into technical methanol catalysts as well as the amount of hydrogen containing intermediates and products during reaction.

ABSTRACT For an economy with hydrogen as the major energy carrier, the development of affordable,... more ABSTRACT For an economy with hydrogen as the major energy carrier, the development of affordable, reliable, sensitive and selective hydrogen sensors is indispensable. In principle, Pd-based optical-fibre sensors could meet such requirements if the cross-contamination effect of the Pd surface by e.g. oxygen, moisture or carbon monoxide can be prevented. Here, we propose the pioneering idea of using a metal–organic framework (MOF) thin film as a tuneable protective coating. As a proof of principle, we demonstrate that homogeneous and continuous MOF coatings can indeed be deposited on Pd surfaces without serious compromise of the sensor's response, opening the way for the optimisation of hydrogen-selective MOF thin films.

The Journal of Physical Chemistry C, 2014

Functionalization of metal−organic frameworks results in higher hydrogen uptakes owing to stronge... more Functionalization of metal−organic frameworks results in higher hydrogen uptakes owing to stronger hydrogen−host interactions. However, it has not been studied whether a given functional group acts on existing adsorption sites (linker or metal) or introduces new ones. In this work, the effect of two types of functional groups on MIL-101 (Cr) is analyzed. Thermal-desorption spectroscopy reveals that the −Br ligand increases the secondary building unit's hydrogen affinity, while the −NH 2 functional group introduces new hydrogen adsorption sites. In addition, a subsequent introduction of −Br and −NH 2 ligands on the linker results in the highest hydrogen-store interaction energy on the cationic nodes. The latter is attributed to a push-and-pull effect of the linkers.

Physical Chemistry Chemical Physics, 2014

Palladium nanoparticles can split the dihydrogen bond and produce atomic hydrogen. When the metal... more Palladium nanoparticles can split the dihydrogen bond and produce atomic hydrogen. When the metal nanoparticles are in intimate contact with a hydrogen-atom host, chemisorption of H-atoms by the host has been suggested to occur via the hydrogen spillover mechanism. Metal-organic frameworks were predicted to be able to act as effective chemisorption sites, and increased ambient-temperature hydrogen adsorption was reported on several occasions. The intimate contact was supposedly ensured by the use of a carbon bridge. In this work, we show that it is possible to introduce catalyst palladium particles into MOF's pores and simultaneously ensuring good contact, making the employment of the carbon bridge redundant. The addition of Pd nanoparticles indeed increases the ambient-temperature hydrogen uptake of the framework, but this is found to be solely due to palladium hydride formation. In addition, we show that the hydrogen atoms do not chemisorb on the host framework, which excludes the possibility of hydrogen spillover.

Physical Chemistry Chemical Physics, 2013

The transformation from the fatuous consumption of fossil energy towards a sustainable energy cir... more The transformation from the fatuous consumption of fossil energy towards a sustainable energy circle is most easily marketable by not changing the underlying energy carrier but generating it from renewable energy. Hydrocarbons can be principally produced from renewable hydrogen and carbon dioxide collected by biomass. However, research is needed to increase the energetic and economic efficiency of the process. We demonstrate the enhancement of CO 2 methanation by sorption enhanced catalysis. The preparation and catalytic activity of sorption catalysts based on Ni particles in zeolites is reported. The functioning of the sorption catalysis is discussed together with the determination of the reaction mechanism, providing implications for new ways in catalysis.

Physical Chemistry Chemical Physics, 2011

The widespread adoption of hydrogen as an energy carrier could bring significant benefits, but on... more The widespread adoption of hydrogen as an energy carrier could bring significant benefits, but only if a number of currently intractable problems can be overcome. Not the least of these is the problem of storage, particularly when aimed at use onboard light-vehicles. The aim of this overview is to look in depth at a number of areas linked by the recently concluded HYDROGEN research network, representing an intentionally multi-faceted selection with the goal of advancing the field on a number of fronts simultaneously. For the general reader we provide a concise outline of the main approaches to storing hydrogen before moving on to detailed reviews of recent research in the solid chemical storage of hydrogen, and so provide an entry point for the interested reader on these diverse topics. The subjects covered include: the mechanisms of Ti catalysis in alanates; the kinetics of the borohydrides and the resulting limitations; novel transition metal catalysts for use with complex hydrides; less common borohydrides; protic-hydridic stores; metal ammines and novel approaches to nano-confined metal hydrides.

International Journal of Hydrogen Energy, 2011

Thin layer coating Microwave heating a b s t r a c t A honeycomb ceramic monolith (HCM) that was ... more Thin layer coating Microwave heating a b s t r a c t A honeycomb ceramic monolith (HCM) that was coated with 0.54 wt% Ni (corresponding to 0.2 micron Ni thin layer) could be heated rapidly from room temperature to white glowing within 7 s under 1000 W microwaves. Energy efficiency to convert microwaves to heat via this Ni-coated HCM was estimated to be more than 90%. By loading metal hydride powder samples into the monolith channels, Ni-HCMs were demonstrated to release 100% hydrogen from MgH 2 and other hydrides (NaBH 4 , NaAlH 4 , and LiH) under 200 W microwaves within 2e3 min. The new microwave/Ni-HCM method offers many advantages over the conventional electrical resistant or microwave heating methods on hydrides, including 1) very fast kinetics, 2) wide application range for various hydrides, 3) simple process with no ball-milling or catalyst addition, and 4) very high energy efficiency. .sg (W.S. Chin).

International Journal of Hydrogen Energy, 2010

Solid state reaction Alkali aluminum hydride a b s t r a c t Solid reactions between alkali alumi... more Solid state reaction Alkali aluminum hydride a b s t r a c t Solid reactions between alkali aluminum hydrides (MAlH 4 , M ¼ Li or Na) and NH 4 Cl (at mole ratio 1:1) at 170 C were investigated quantitatively using temperature programmed reaction (TPR), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC) and

Frontiers of Chemical Engineering in China, 2010

The use of carbon dioxide (CO2) and calcium-containing by-products from industrial activities is ... more The use of carbon dioxide (CO2) and calcium-containing by-products from industrial activities is receiving increasing interest as a route to valuable carbonate materials while reducing CO2 emissions and saving natural resources. In this work, wet-chemical experimental data was assessed, which involved the carbonation of three types of materials in aqueous solutions, namely, 1) wollastonite, a calcium silicate mineral, 2) steelmaking

Environmental Science & Technology, 2011

Global energy consumption will at least double during this century. Today about 80% of the primar... more Global energy consumption will at least double during this century. Today about 80% of the primary energy used is provided by fossil fuels. To avoid anthropogenic climate change, it is essential that the world's energy system is gradually transformed from fossil energy based to a solar based one. In such a solar world, efficient energy storage is prerequisite to deal with the intermittency of this abundant source. Storage in the form of chemical energy, that is, solar fuels, provides a natural route to deal with this problem. An obvious solar fuel would be hydrogen, which can be produced efficiently from solar energy through direct splitting of water or through combination of solar electricity production with electrolysis of water. 1 Unfortunately, hydrogen has a major disadvantage as its transport and storage is not trivial. No such storage problem exists for alcohols or liquid hydrocarbons. Especially liquid hydrocarbons are preferred solar fuels in view of their unprecedented combination of gravimetric and volumetric energy density and the worldwide existing markets and infrastructure.

Chemical Engineering & Technology, 2010

... Conditions: CaCl2 2.44 mol/L, temperature 25 °C, pressure 5 MPa. ... Among the different poly... more ... Conditions: CaCl2 2.44 mol/L, temperature 25 °C, pressure 5 MPa. ... Among the different polymorphs of calcium carbonate, calcite is of great interest because of its wide use as a ... obtained by other research groups [13], are due to the high supersaturation in the aqueous solution. ...

Chemical Engineering & Technology, 2012

A new indirect mineral carbonation process is studied which could mitigate anthropogenic CO 2 emi... more A new indirect mineral carbonation process is studied which could mitigate anthropogenic CO 2 emissions. In this process, magnesium silicate is dissolved in HCl and the resulting MgCl 2 solution is subsequently reacted with CO 2 in NH 3 . HCl and NH 3 are recovered from NH 4 Cl in a two-step thermal decomposition. Carbonation is investigated from 30°C to 180°C at 4 MPa CO 2 pressure and Mg-carbonate morphology transformations with increasing temperature are identified. Nesquehonite (MgCO 3 · 3H 2 O) is obtained below 70°C, hydromagnesite (Mg 5 (CO 3 ) 4 (OH) 2 · 4H 2 O) is formed at 100°C, and further temperature increase to 180°C leads to magnesite (MgCO 3 ) precipitation. Nesquehonite and magnesite can fix more CO 2 per mole Mg than hydromagnesite.

Carbonation of abundantly available magnesium silicates such as serpentinites could be an attract... more Carbonation of abundantly available magnesium silicates such as serpentinites could be an attractive route to capture and store CO2. In this paper we describe a novel route to produce magnesium hydroxide, Mg(OH)2, from Finnish serpentinite. The resulting Mg(OH)2 is much more reactive towards CO2 than the parent serpentinite. The process route of producing Mg(OH)2 as reported here involves a staged process of Mg extraction using a moderately high temperature solid/solid reaction of serpentinite and ammonium sulphate (AS) salt followed by precipitation of Mg(OH)2 using aqueous ammonia. Tests at 400–550 °C showed promising results. An optimum range of reaction conditions for the extraction stage (Mg extraction) and precipitation stages (production of valuable products) of the process was also identified. The valuable solid products refer to Fe-containing compound (dark brown solid, exhibiting the properties of FeOOH) and Mg(OH)2 (white precipitate), both precipitated in an aqueous solution with 25% (v/v) ammonia at pH 8–9 and 11–12, respectively. In some cases all Mg extracted from serpentinite was converted to magnesium Mg(OH)2 with very small volumes of ammonia solution added. Apart from the relatively cheap AS salt reagent, the prospect of recovery and use of by-products of the process: ammonia gas, FeOOH, and AS salt presents significant benefits.

Catal. Sci. Technol., 2015

We demonstrate that the kinetics of the Sabatier reaction catalysed by sorption catalysts depends... more We demonstrate that the kinetics of the Sabatier reaction catalysed by sorption catalysts depends on the nanostructure of the catalyst–sorbent system, and in particular on the shape selectivity of the zeolite sorbent.

Energy Procedia, 2011

Two experimental modes of operation, a sequence of batch and a continuous one, have demonstrated ... more Two experimental modes of operation, a sequence of batch and a continuous one, have demonstrated the technical feasibility of Shell’s proposed slurry-based direct flue gas mineralization concept on the basis of activated serpentine. The base case mineralization concept can be simplified yielding a variety of product forms and significantly reduced CO2 abatement costs. Combined with a positive first assessment of

Physical Chemistry Chemical Physics

Neutron imaging reveals the amount of hydrogen intercalated into technical methanol catalysts as ... more Neutron imaging reveals the amount of hydrogen intercalated into technical methanol catalysts as well as the amount of hydrogen containing intermediates and products during reaction.

ABSTRACT For an economy with hydrogen as the major energy carrier, the development of affordable,... more ABSTRACT For an economy with hydrogen as the major energy carrier, the development of affordable, reliable, sensitive and selective hydrogen sensors is indispensable. In principle, Pd-based optical-fibre sensors could meet such requirements if the cross-contamination effect of the Pd surface by e.g. oxygen, moisture or carbon monoxide can be prevented. Here, we propose the pioneering idea of using a metal–organic framework (MOF) thin film as a tuneable protective coating. As a proof of principle, we demonstrate that homogeneous and continuous MOF coatings can indeed be deposited on Pd surfaces without serious compromise of the sensor's response, opening the way for the optimisation of hydrogen-selective MOF thin films.

The Journal of Physical Chemistry C, 2014

Functionalization of metal−organic frameworks results in higher hydrogen uptakes owing to stronge... more Functionalization of metal−organic frameworks results in higher hydrogen uptakes owing to stronger hydrogen−host interactions. However, it has not been studied whether a given functional group acts on existing adsorption sites (linker or metal) or introduces new ones. In this work, the effect of two types of functional groups on MIL-101 (Cr) is analyzed. Thermal-desorption spectroscopy reveals that the −Br ligand increases the secondary building unit's hydrogen affinity, while the −NH 2 functional group introduces new hydrogen adsorption sites. In addition, a subsequent introduction of −Br and −NH 2 ligands on the linker results in the highest hydrogen-store interaction energy on the cationic nodes. The latter is attributed to a push-and-pull effect of the linkers.

Physical Chemistry Chemical Physics, 2014

Palladium nanoparticles can split the dihydrogen bond and produce atomic hydrogen. When the metal... more Palladium nanoparticles can split the dihydrogen bond and produce atomic hydrogen. When the metal nanoparticles are in intimate contact with a hydrogen-atom host, chemisorption of H-atoms by the host has been suggested to occur via the hydrogen spillover mechanism. Metal-organic frameworks were predicted to be able to act as effective chemisorption sites, and increased ambient-temperature hydrogen adsorption was reported on several occasions. The intimate contact was supposedly ensured by the use of a carbon bridge. In this work, we show that it is possible to introduce catalyst palladium particles into MOF's pores and simultaneously ensuring good contact, making the employment of the carbon bridge redundant. The addition of Pd nanoparticles indeed increases the ambient-temperature hydrogen uptake of the framework, but this is found to be solely due to palladium hydride formation. In addition, we show that the hydrogen atoms do not chemisorb on the host framework, which excludes the possibility of hydrogen spillover.

Physical Chemistry Chemical Physics, 2013

The transformation from the fatuous consumption of fossil energy towards a sustainable energy cir... more The transformation from the fatuous consumption of fossil energy towards a sustainable energy circle is most easily marketable by not changing the underlying energy carrier but generating it from renewable energy. Hydrocarbons can be principally produced from renewable hydrogen and carbon dioxide collected by biomass. However, research is needed to increase the energetic and economic efficiency of the process. We demonstrate the enhancement of CO 2 methanation by sorption enhanced catalysis. The preparation and catalytic activity of sorption catalysts based on Ni particles in zeolites is reported. The functioning of the sorption catalysis is discussed together with the determination of the reaction mechanism, providing implications for new ways in catalysis.

Physical Chemistry Chemical Physics, 2011

The widespread adoption of hydrogen as an energy carrier could bring significant benefits, but on... more The widespread adoption of hydrogen as an energy carrier could bring significant benefits, but only if a number of currently intractable problems can be overcome. Not the least of these is the problem of storage, particularly when aimed at use onboard light-vehicles. The aim of this overview is to look in depth at a number of areas linked by the recently concluded HYDROGEN research network, representing an intentionally multi-faceted selection with the goal of advancing the field on a number of fronts simultaneously. For the general reader we provide a concise outline of the main approaches to storing hydrogen before moving on to detailed reviews of recent research in the solid chemical storage of hydrogen, and so provide an entry point for the interested reader on these diverse topics. The subjects covered include: the mechanisms of Ti catalysis in alanates; the kinetics of the borohydrides and the resulting limitations; novel transition metal catalysts for use with complex hydrides; less common borohydrides; protic-hydridic stores; metal ammines and novel approaches to nano-confined metal hydrides.

International Journal of Hydrogen Energy, 2011

Thin layer coating Microwave heating a b s t r a c t A honeycomb ceramic monolith (HCM) that was ... more Thin layer coating Microwave heating a b s t r a c t A honeycomb ceramic monolith (HCM) that was coated with 0.54 wt% Ni (corresponding to 0.2 micron Ni thin layer) could be heated rapidly from room temperature to white glowing within 7 s under 1000 W microwaves. Energy efficiency to convert microwaves to heat via this Ni-coated HCM was estimated to be more than 90%. By loading metal hydride powder samples into the monolith channels, Ni-HCMs were demonstrated to release 100% hydrogen from MgH 2 and other hydrides (NaBH 4 , NaAlH 4 , and LiH) under 200 W microwaves within 2e3 min. The new microwave/Ni-HCM method offers many advantages over the conventional electrical resistant or microwave heating methods on hydrides, including 1) very fast kinetics, 2) wide application range for various hydrides, 3) simple process with no ball-milling or catalyst addition, and 4) very high energy efficiency. .sg (W.S. Chin).

International Journal of Hydrogen Energy, 2010

Solid state reaction Alkali aluminum hydride a b s t r a c t Solid reactions between alkali alumi... more Solid state reaction Alkali aluminum hydride a b s t r a c t Solid reactions between alkali aluminum hydrides (MAlH 4 , M ¼ Li or Na) and NH 4 Cl (at mole ratio 1:1) at 170 C were investigated quantitatively using temperature programmed reaction (TPR), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC) and

Frontiers of Chemical Engineering in China, 2010

The use of carbon dioxide (CO2) and calcium-containing by-products from industrial activities is ... more The use of carbon dioxide (CO2) and calcium-containing by-products from industrial activities is receiving increasing interest as a route to valuable carbonate materials while reducing CO2 emissions and saving natural resources. In this work, wet-chemical experimental data was assessed, which involved the carbonation of three types of materials in aqueous solutions, namely, 1) wollastonite, a calcium silicate mineral, 2) steelmaking

Environmental Science & Technology, 2011

Global energy consumption will at least double during this century. Today about 80% of the primar... more Global energy consumption will at least double during this century. Today about 80% of the primary energy used is provided by fossil fuels. To avoid anthropogenic climate change, it is essential that the world's energy system is gradually transformed from fossil energy based to a solar based one. In such a solar world, efficient energy storage is prerequisite to deal with the intermittency of this abundant source. Storage in the form of chemical energy, that is, solar fuels, provides a natural route to deal with this problem. An obvious solar fuel would be hydrogen, which can be produced efficiently from solar energy through direct splitting of water or through combination of solar electricity production with electrolysis of water. 1 Unfortunately, hydrogen has a major disadvantage as its transport and storage is not trivial. No such storage problem exists for alcohols or liquid hydrocarbons. Especially liquid hydrocarbons are preferred solar fuels in view of their unprecedented combination of gravimetric and volumetric energy density and the worldwide existing markets and infrastructure.

Chemical Engineering & Technology, 2010

... Conditions: CaCl2 2.44 mol/L, temperature 25 °C, pressure 5 MPa. ... Among the different poly... more ... Conditions: CaCl2 2.44 mol/L, temperature 25 °C, pressure 5 MPa. ... Among the different polymorphs of calcium carbonate, calcite is of great interest because of its wide use as a ... obtained by other research groups [13], are due to the high supersaturation in the aqueous solution. ...

Chemical Engineering & Technology, 2012

A new indirect mineral carbonation process is studied which could mitigate anthropogenic CO 2 emi... more A new indirect mineral carbonation process is studied which could mitigate anthropogenic CO 2 emissions. In this process, magnesium silicate is dissolved in HCl and the resulting MgCl 2 solution is subsequently reacted with CO 2 in NH 3 . HCl and NH 3 are recovered from NH 4 Cl in a two-step thermal decomposition. Carbonation is investigated from 30°C to 180°C at 4 MPa CO 2 pressure and Mg-carbonate morphology transformations with increasing temperature are identified. Nesquehonite (MgCO 3 · 3H 2 O) is obtained below 70°C, hydromagnesite (Mg 5 (CO 3 ) 4 (OH) 2 · 4H 2 O) is formed at 100°C, and further temperature increase to 180°C leads to magnesite (MgCO 3 ) precipitation. Nesquehonite and magnesite can fix more CO 2 per mole Mg than hydromagnesite.

Carbonation of abundantly available magnesium silicates such as serpentinites could be an attract... more Carbonation of abundantly available magnesium silicates such as serpentinites could be an attractive route to capture and store CO2. In this paper we describe a novel route to produce magnesium hydroxide, Mg(OH)2, from Finnish serpentinite. The resulting Mg(OH)2 is much more reactive towards CO2 than the parent serpentinite. The process route of producing Mg(OH)2 as reported here involves a staged process of Mg extraction using a moderately high temperature solid/solid reaction of serpentinite and ammonium sulphate (AS) salt followed by precipitation of Mg(OH)2 using aqueous ammonia. Tests at 400–550 °C showed promising results. An optimum range of reaction conditions for the extraction stage (Mg extraction) and precipitation stages (production of valuable products) of the process was also identified. The valuable solid products refer to Fe-containing compound (dark brown solid, exhibiting the properties of FeOOH) and Mg(OH)2 (white precipitate), both precipitated in an aqueous solution with 25% (v/v) ammonia at pH 8–9 and 11–12, respectively. In some cases all Mg extracted from serpentinite was converted to magnesium Mg(OH)2 with very small volumes of ammonia solution added. Apart from the relatively cheap AS salt reagent, the prospect of recovery and use of by-products of the process: ammonia gas, FeOOH, and AS salt presents significant benefits.