Ruben van Duren - Academia.edu (original) (raw)

Papers by Ruben van Duren

Research paper thumbnail of CCDC 275889: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 270182: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 630063: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of Selective paraffin cracking : the selective cracking of paraffins to small olefins over bifunctional catalysts

Research paper thumbnail of Effect of sequential catalyst regeneration in catalytic fast pyrolysis of biomass

Fast pyrolysis is a thermochemical process that contributes to the conversion of biomass into a v... more Fast pyrolysis is a thermochemical process that contributes to the conversion of biomass into a variety of fuels and chemicals. The process aims to produce a liquid mixture of organic molecules called bio-oil. To improve the quality of crude bio-oil in relation to biofuel applications, biomass fast pyrolysis can be carried out in the presence of suitable catalysts. Catalyst particles can be introduced to the reactor (in situ) for the removal of oxygen and the catalytic cracking of high molecular weight compounds in the pyrolysis vapours. The primary goal of this work was to investigate the effects of a repeatedly regenerated ZSM-5 based FCC catalyst on the fast pyrolysis product yields (e.g. organics, water, carbonaceous solids and non-condensable gases), non-condensable gas compositions, bio-oil compositions and the elemental distribution over various pyrolysis products and to gain an insight of the underlying mechanisms. Experiments were performed in a newly designed laboratory sc...

Research paper thumbnail of 99/01071 Catalytic fast pyrolysis of biomass

Fuel and Energy Abstracts, 1999

Research paper thumbnail of Deep Deoxygenation of Biocrudes Utilizing Fluidized Catalytic Cracking Co-Processing with Hydrocarbon Feedstocks

Research paper thumbnail of In situ performance of various metal doped catalysts in micro-pyrolysis and continuous fast pyrolysis

Fuel Processing Technology, 2016

Research paper thumbnail of Challenges in the design and operation of processes for catalytic fast pyrolysis of woody biomass

Renewable and Sustainable Energy Reviews, 2016

With respect to the application of upgraded oils derived from biomass materials, the goal is to p... more With respect to the application of upgraded oils derived from biomass materials, the goal is to produce either high yields of transportation fuel compounds (e.g. aromatics, olefins) and specialty chemicals (e.g. phenolics), or just a drop-in refinery feedstock to be blended with the feed streams of existing petroleum refineries. It has already been recognized in the early days of fast pyrolysis RD in- or ex situ) and design elements (e.g. reactor type, catalyst type) on one hand, and definitions and outcomes of possible obstacles (e.g. successive regeneration of the catalyst, effect of biomass ash) on the other. In this paper, the efficient and economical use of the primary and secondary products, and the heat integration of the process is discussed. Moreover, some process alternatives for an efficient CFP operation are suggested.

Research paper thumbnail of Effect of biomass ash in catalytic fast pyrolysis of pine wood

Applied Catalysis B: Environmental, 2015

Research paper thumbnail of Catalytic fast pyrolysis of pine wood: Effect of successive catalyst regeneration

Research paper thumbnail of Platinum Complexes of Rigid Bidentate Phosphine Ligands in the Hydroformylation of 1-Octene

Organometallics, 2005

The synthesis of diphosphine compounds 1 and 2, derived from a terphenyl backbone, and their corr... more The synthesis of diphosphine compounds 1 and 2, derived from a terphenyl backbone, and their corresponding cis coordination in platinum complexes is described. Subtle but significant differences are noted in the solid-state structures, with bite angles P1-Pt-P2 of ...

Research paper thumbnail of An attempt to predict the optimum zeolite-based catalyst for selective cracking of naphtha-range hydrocarbons to light olefins

Journal of Molecular Catalysis A: Chemical, 2002

Theoretical calculations were performed in order to determine, a priori, which in a range of smal... more Theoretical calculations were performed in order to determine, a priori, which in a range of small-to-medium pore zeolites would be the most effective at suppressing hydride transfer reactions by estimating the magnitude of steric hindrance. Steric hindrance was estimated as the difference between the enthalpies of adsorption of the transition-state complex and those of the two reacting hydrocarbons, calculated using

Research paper thumbnail of Chiral (Diphosphonite)platinum Complexes in Asymmetric Hydroformylation

Helvetica Chimica Acta, 2006

The chiral diphosphonite ligand (11bR,11′bR)‐4,4′‐(9,9‐dimethyl‐9H‐xanthene‐4,5‐diyl)bis[dinaphth... more The chiral diphosphonite ligand (11bR,11′bR)‐4,4′‐(9,9‐dimethyl‐9H‐xanthene‐4,5‐diyl)bis[dinaphtho[2,1‐d:1′,2′‐f][1,3,2]dioxaphosphepin] ((R,R)‐XantBino; (R)‐1), based on a rigid xanthene backbone, was applied in the Pt/Sn‐catalyzed hydroformylation of styrene (4a), 4‐methylstyrene (4b), vinyl acetate (4c), and allyl acetate (4d), by using a Pt/Sn ratio of 1 : 1. High ee of up to 80% were observed, along with good regioselectivities towards the desired branched aldehydes. For styrene, an interesting inversion in the stereoselection process was observed at elevated temperatures, and a mechanism is proposed considering the temperature dependence of the regioselectivity. The complex [PtCl2{(S,S)‐XantBino}] ((S)‐2) was characterized by X‐ray crystal‐structure analysis, revealing an unusual out‐of‐plane ligand coordination of the metal fragment. The complex [PtCl(SnCl3){(R,R)‐XantBino}] ((R)‐3) was characterized by means of 31P‐NMR spectroscopy.

Research paper thumbnail of Platinum-catalyzed hydroformylation of terminal and internal octenes

Dalton Transactions, 2007

A brief historic overview of Pt/Sn-catalyzed hydroformylation as well as recent advances in the h... more A brief historic overview of Pt/Sn-catalyzed hydroformylation as well as recent advances in the hydroformylation of internal alkenes is provided. This serves as background for the results obtained with the [Pt(Sixantphos)Cl(2)] system, for which the molecular structure and the spectroscopic data are described. Insitu UV/Vis-spectroscopic studies have revealed rapid formation of the corresponding Pt-stannate complex upon reaction with SnCl(2), whereas high-pressure insitu IR-spectroscopy showed formation of a Pt-CO species and a short-lived Pt-H species under syngas, as well as rapid evolution of aldehyde product upon addition of 1-octene to the preformed catalyst in the IR autoclave. The hydroformylation of 1-octene and the i-octenes has been performed. For the internal alkenes, selective tandem isomerization/hydroformylation towards n-nonanal is observed with this catalyst system.

Research paper thumbnail of Platinum catalyzed hydroformylation

Research paper thumbnail of Validation of a new set-up for continuous catalytic fast pyrolysis of biomass coupled with vapour phase upgrading

Journal of Analytical and Applied Pyrolysis, 2013

A fully controlled, continuously operated mini-plant has been designed and constructed based on a... more A fully controlled, continuously operated mini-plant has been designed and constructed based on auger reactor technology. Three types of biomass fast pyrolysis experiments were performed in this setup , viz. non-catalytic, in situ catalytic fast pyrolysis and ex situ upgrading of non-catalytic fast pyrolysis vapours by means of a downstream, moving-bed catalytic reactor. Pine wood was selected as the reference biomass feedstock. The mini-plant enables variation of the catalyst loading and contact times while producing larger samples suitable for full characterization in continuous operation. Due to short catalyst residence times and the fact that the biomass fed to the reactor is always brought into contact with fresh catalyst (in case of in situ catalysis) or the pyrolysis vapours always contact with fresh catalyst in the moving bed catalytic reactor (in case of ex situ catalysis), catalyst deactivation and coking are prevented ensuring improved experimental repeatability in catalytic pyrolysis experiments. The performance of the system was verified by in-and ex situ application of a single type of heterogeneous ZSM-5 based acidic catalyst while the non-catalytic results were taken as reference. Catalytic fast pyrolysis results in more effective oxygen removal from the bio-oil in the form of water, and resulting in lower yields of the organic fraction. Moreover catalytic decarbonylation reactions gave rise to increased gas yields. With in-and ex situ catalysis, increases in the char yields were observed as well as coke deposition on the catalyst surface. GC × GC-FID and GC × GC-TOF-MS analysis of the produced bio-oils showed that the use of in-and ex situ catalysis causes conversion of high molecular weight compounds to lower ones. Disappearance of detectable sugars and aldehydes, a decrease of the yield of acids, formation of phenols, and favoured aromatics production were the other catalytic effects observed.

Research paper thumbnail of CCDC 275889: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 270182: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 630063: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of Selective paraffin cracking : the selective cracking of paraffins to small olefins over bifunctional catalysts

Research paper thumbnail of Effect of sequential catalyst regeneration in catalytic fast pyrolysis of biomass

Fast pyrolysis is a thermochemical process that contributes to the conversion of biomass into a v... more Fast pyrolysis is a thermochemical process that contributes to the conversion of biomass into a variety of fuels and chemicals. The process aims to produce a liquid mixture of organic molecules called bio-oil. To improve the quality of crude bio-oil in relation to biofuel applications, biomass fast pyrolysis can be carried out in the presence of suitable catalysts. Catalyst particles can be introduced to the reactor (in situ) for the removal of oxygen and the catalytic cracking of high molecular weight compounds in the pyrolysis vapours. The primary goal of this work was to investigate the effects of a repeatedly regenerated ZSM-5 based FCC catalyst on the fast pyrolysis product yields (e.g. organics, water, carbonaceous solids and non-condensable gases), non-condensable gas compositions, bio-oil compositions and the elemental distribution over various pyrolysis products and to gain an insight of the underlying mechanisms. Experiments were performed in a newly designed laboratory sc...

Research paper thumbnail of 99/01071 Catalytic fast pyrolysis of biomass

Fuel and Energy Abstracts, 1999

Research paper thumbnail of Deep Deoxygenation of Biocrudes Utilizing Fluidized Catalytic Cracking Co-Processing with Hydrocarbon Feedstocks

Research paper thumbnail of In situ performance of various metal doped catalysts in micro-pyrolysis and continuous fast pyrolysis

Fuel Processing Technology, 2016

Research paper thumbnail of Challenges in the design and operation of processes for catalytic fast pyrolysis of woody biomass

Renewable and Sustainable Energy Reviews, 2016

With respect to the application of upgraded oils derived from biomass materials, the goal is to p... more With respect to the application of upgraded oils derived from biomass materials, the goal is to produce either high yields of transportation fuel compounds (e.g. aromatics, olefins) and specialty chemicals (e.g. phenolics), or just a drop-in refinery feedstock to be blended with the feed streams of existing petroleum refineries. It has already been recognized in the early days of fast pyrolysis RD in- or ex situ) and design elements (e.g. reactor type, catalyst type) on one hand, and definitions and outcomes of possible obstacles (e.g. successive regeneration of the catalyst, effect of biomass ash) on the other. In this paper, the efficient and economical use of the primary and secondary products, and the heat integration of the process is discussed. Moreover, some process alternatives for an efficient CFP operation are suggested.

Research paper thumbnail of Effect of biomass ash in catalytic fast pyrolysis of pine wood

Applied Catalysis B: Environmental, 2015

Research paper thumbnail of Catalytic fast pyrolysis of pine wood: Effect of successive catalyst regeneration

Research paper thumbnail of Platinum Complexes of Rigid Bidentate Phosphine Ligands in the Hydroformylation of 1-Octene

Organometallics, 2005

The synthesis of diphosphine compounds 1 and 2, derived from a terphenyl backbone, and their corr... more The synthesis of diphosphine compounds 1 and 2, derived from a terphenyl backbone, and their corresponding cis coordination in platinum complexes is described. Subtle but significant differences are noted in the solid-state structures, with bite angles P1-Pt-P2 of ...

Research paper thumbnail of An attempt to predict the optimum zeolite-based catalyst for selective cracking of naphtha-range hydrocarbons to light olefins

Journal of Molecular Catalysis A: Chemical, 2002

Theoretical calculations were performed in order to determine, a priori, which in a range of smal... more Theoretical calculations were performed in order to determine, a priori, which in a range of small-to-medium pore zeolites would be the most effective at suppressing hydride transfer reactions by estimating the magnitude of steric hindrance. Steric hindrance was estimated as the difference between the enthalpies of adsorption of the transition-state complex and those of the two reacting hydrocarbons, calculated using

Research paper thumbnail of Chiral (Diphosphonite)platinum Complexes in Asymmetric Hydroformylation

Helvetica Chimica Acta, 2006

The chiral diphosphonite ligand (11bR,11′bR)‐4,4′‐(9,9‐dimethyl‐9H‐xanthene‐4,5‐diyl)bis[dinaphth... more The chiral diphosphonite ligand (11bR,11′bR)‐4,4′‐(9,9‐dimethyl‐9H‐xanthene‐4,5‐diyl)bis[dinaphtho[2,1‐d:1′,2′‐f][1,3,2]dioxaphosphepin] ((R,R)‐XantBino; (R)‐1), based on a rigid xanthene backbone, was applied in the Pt/Sn‐catalyzed hydroformylation of styrene (4a), 4‐methylstyrene (4b), vinyl acetate (4c), and allyl acetate (4d), by using a Pt/Sn ratio of 1 : 1. High ee of up to 80% were observed, along with good regioselectivities towards the desired branched aldehydes. For styrene, an interesting inversion in the stereoselection process was observed at elevated temperatures, and a mechanism is proposed considering the temperature dependence of the regioselectivity. The complex [PtCl2{(S,S)‐XantBino}] ((S)‐2) was characterized by X‐ray crystal‐structure analysis, revealing an unusual out‐of‐plane ligand coordination of the metal fragment. The complex [PtCl(SnCl3){(R,R)‐XantBino}] ((R)‐3) was characterized by means of 31P‐NMR spectroscopy.

Research paper thumbnail of Platinum-catalyzed hydroformylation of terminal and internal octenes

Dalton Transactions, 2007

A brief historic overview of Pt/Sn-catalyzed hydroformylation as well as recent advances in the h... more A brief historic overview of Pt/Sn-catalyzed hydroformylation as well as recent advances in the hydroformylation of internal alkenes is provided. This serves as background for the results obtained with the [Pt(Sixantphos)Cl(2)] system, for which the molecular structure and the spectroscopic data are described. Insitu UV/Vis-spectroscopic studies have revealed rapid formation of the corresponding Pt-stannate complex upon reaction with SnCl(2), whereas high-pressure insitu IR-spectroscopy showed formation of a Pt-CO species and a short-lived Pt-H species under syngas, as well as rapid evolution of aldehyde product upon addition of 1-octene to the preformed catalyst in the IR autoclave. The hydroformylation of 1-octene and the i-octenes has been performed. For the internal alkenes, selective tandem isomerization/hydroformylation towards n-nonanal is observed with this catalyst system.

Research paper thumbnail of Platinum catalyzed hydroformylation

Research paper thumbnail of Validation of a new set-up for continuous catalytic fast pyrolysis of biomass coupled with vapour phase upgrading

Journal of Analytical and Applied Pyrolysis, 2013

A fully controlled, continuously operated mini-plant has been designed and constructed based on a... more A fully controlled, continuously operated mini-plant has been designed and constructed based on auger reactor technology. Three types of biomass fast pyrolysis experiments were performed in this setup , viz. non-catalytic, in situ catalytic fast pyrolysis and ex situ upgrading of non-catalytic fast pyrolysis vapours by means of a downstream, moving-bed catalytic reactor. Pine wood was selected as the reference biomass feedstock. The mini-plant enables variation of the catalyst loading and contact times while producing larger samples suitable for full characterization in continuous operation. Due to short catalyst residence times and the fact that the biomass fed to the reactor is always brought into contact with fresh catalyst (in case of in situ catalysis) or the pyrolysis vapours always contact with fresh catalyst in the moving bed catalytic reactor (in case of ex situ catalysis), catalyst deactivation and coking are prevented ensuring improved experimental repeatability in catalytic pyrolysis experiments. The performance of the system was verified by in-and ex situ application of a single type of heterogeneous ZSM-5 based acidic catalyst while the non-catalytic results were taken as reference. Catalytic fast pyrolysis results in more effective oxygen removal from the bio-oil in the form of water, and resulting in lower yields of the organic fraction. Moreover catalytic decarbonylation reactions gave rise to increased gas yields. With in-and ex situ catalysis, increases in the char yields were observed as well as coke deposition on the catalyst surface. GC × GC-FID and GC × GC-TOF-MS analysis of the produced bio-oils showed that the use of in-and ex situ catalysis causes conversion of high molecular weight compounds to lower ones. Disappearance of detectable sugars and aldehydes, a decrease of the yield of acids, formation of phenols, and favoured aromatics production were the other catalytic effects observed.