126
|
Rohling RY, Hensen EJM, Pidko EA. Multi-site Cooperativity in Alkali-Metal-Exchanged Faujasites for the Production of Biomass-Derived Aromatics. Chemphyschem 2018; 19:446-458. [PMID: 29105288 PMCID: PMC5820756 DOI: 10.1002/cphc.201701058] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 11/03/2017] [Indexed: 12/21/2022]
Abstract
The catalytic Diels-Alder cycloaddition-dehydration (DACD) reaction of furanics with ethylene is a promising route to bio-derived aromatics. The reaction can be catalyzed by alkali-metal-exchanged faujasites. Herein, the results of periodic DFT calculations based on accurate structural models of alkali-metal-exchanged zeolites are presented, revealing the fundamental roles that confinement and the nature of the exchangeable cations in zeolite micropores have in the performance of faujasite-based catalysts in the DACD reaction. Special attention is devoted to analyzing the effect of functional substituents on furanic substrates (furan, 2,5-dimethylfuran, 2,5-furandicarboxylic acid) on the catalyst behavior. It is demonstrated that the conventional reactivity theories of the Diels-Alder chemistry based on simplistic single-site Lewis acidity and substituent effects do not apply if catalytic processes in the multiple-site confined environment of zeolite nanopores are considered. The nature and cooperativity of the interactions between the multiple exchangeable cations and the substrates determine the reaction energetics of the elementary steps involved in the DACD process.
Collapse
|
127
|
Rohling R, Uslamin E, Zijlstra B, Tranca IC, Filot IAW, Hensen EJM, Pidko EA. An Active Alkali-Exchanged Faujasite Catalyst for p-Xylene Production via the One-Pot Diels-Alder Cycloaddition/Dehydration Reaction of 2,5-Dimethylfuran with Ethylene. ACS Catal 2018; 8:760-769. [PMID: 29430331 PMCID: PMC5805402 DOI: 10.1021/acscatal.7b03343] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 12/01/2017] [Indexed: 11/29/2022]
Abstract
The one-pot Diels-Alder cycloaddition (DAC)/dehydration (D) tandem reaction between 2,5-dimethylfuran and ethylene is a potent pathway toward biomass-derived p-xylene. In this work, we present a cheap and active low-silica potassium-exchanged faujasite (KY, Si/Al = 2.6) catalyst. Catalyst optimization was guided by a computational study of the DAC/D reaction mechanism over different alkali-exchanged faujasites using periodic density functional theory calculations complemented by microkinetic modeling. Two types of faujasite models were compared, i.e., a high-silica alkali-exchanged faujasite model representing isolated active cation sites and a low-silica alkali-exchanged faujasite in which the reaction involves several cations in the proximity. The mechanistic study points to a significant synergetic cooperative effect of the ensemble of cations in the faujasite supercage on the DAC/D reaction. Alignment of the reactants by their interactions with the cationic sites and stabilization of reaction intermediates contribute to the high catalytic performance. Experiments confirmed the prediction that KY is the most active catalyst among low-silica alkali-exchanged faujasites. This work is an example of how the catalytic reactivity of zeolites depends on multiple interactions between the zeolite and reagents.
Collapse
|
128
|
Chen W, Kimpel TF, Song Y, Chiang FK, Zijlstra B, Pestman R, Wang P, Hensen EJM. Influence of Carbon Deposits on the Cobalt-Catalyzed Fischer-Tropsch Reaction: Evidence of a Two-Site Reaction Model. ACS Catal 2018; 8:1580-1590. [PMID: 29910971 PMCID: PMC5997462 DOI: 10.1021/acscatal.7b03639] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/07/2017] [Indexed: 11/28/2022]
Abstract
One of the well-known observations in the Fischer-Tropsch (FT) reaction is that the CH4 selectivity for cobalt catalysts is always higher than the value expected on the basis of the Anderson-Schulz-Flory (ASF) distribution. Depositing graphitic carbon on a cobalt catalyst strongly suppresses this non-ASF CH4, while the formation of higher hydrocarbons is much less affected. Carbon was laid down on the cobalt catalyst via the Boudouard reaction. We provide evidence that the amorphous carbon does not influence the FT reaction, as it can be easily hydrogenated under reaction conditions. Graphitic carbon is rapidly formed and cannot be removed. This unreactive form of carbon is located on terrace sites and mainly decreases the CO conversion by limiting CH4 formation. Despite nearly unchanged higher hydrocarbon yield, the presence of graphitic carbon enhances the chain-growth probability and strongly suppresses olefin hydrogenation. We demonstrate that graphitic carbon will slowly deposit on the cobalt catalysts during CO hydrogenation, thereby influencing CO conversion and the FT product distribution in a way similar to that for predeposited graphitic carbon. We also demonstrate that the buildup of graphitic carbon by 13CO increases the rate of C-C coupling during the 12C3H6 hydrogenation reaction, whose products follow an ASF-type product distribution of the FT reaction. We explain these results by a two-site model on the basis of insights into structure sensitivity of the underlying reaction steps in the FT mechanism: carbon formed on step-edge sites is involved in chain growth or can migrate to terrace sites, where it is rapidly hydrogenated to CH4. The primary olefinic FT products are predominantly hydrogenated on terrace sites. Covering the terraces by graphitic carbon increases the residence time of CH x intermediates, in line with decreased CH4 selectivity and increased chain-growth rate.
Collapse
|
129
|
Kosinov N, Wijpkema ASG, Uslamin E, Rohling R, Coumans FJAG, Mezari B, Parastaev A, Poryvaev AS, Fedin MV, Pidko EA, Hensen EJM. Innentitelbild: Confined Carbon Mediating Dehydroaromatization of Methane over Mo/ZSM-5 (Angew. Chem. 4/2018). Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201713047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
130
|
Kosinov N, Wijpkema ASG, Uslamin E, Rohling R, Coumans FJAG, Mezari B, Parastaev A, Poryvaev AS, Fedin MV, Pidko EA, Hensen EJM. Confined Carbon Mediating Dehydroaromatization of Methane over Mo/ZSM-5. Angew Chem Int Ed Engl 2018; 57:1016-1020. [PMID: 29181863 PMCID: PMC5820752 DOI: 10.1002/anie.201711098] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Revised: 11/25/2017] [Indexed: 11/10/2022]
Abstract
Non-oxidative dehydroaromatization of methane (MDA) is a promising catalytic process for direct valorization of natural gas to liquid hydrocarbons. The application of this reaction in practical technology is hindered by a lack of understanding about the mechanism and nature of the active sites in benchmark zeolite-based Mo/ZSM-5 catalysts, which precludes the solution of problems such as rapid catalyst deactivation. By applying spectroscopy and microscopy, it is shown that the active centers in Mo/ZSM-5 are partially reduced single-atom Mo sites stabilized by the zeolite framework. By combining a pulse reaction technique with isotope labeling of methane, MDA is shown to be governed by a hydrocarbon pool mechanism in which benzene is derived from secondary reactions of confined polyaromatic carbon species with the initial products of methane activation.
Collapse
|
131
|
Kosinov N, Wijpkema ASG, Uslamin E, Rohling R, Coumans FJAG, Mezari B, Parastaev A, Poryvaev AS, Fedin MV, Pidko EA, Hensen EJM. Inside Cover: Confined Carbon Mediating Dehydroaromatization of Methane over Mo/ZSM-5 (Angew. Chem. Int. Ed. 4/2018). Angew Chem Int Ed Engl 2018. [DOI: 10.1002/anie.201713047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
132
|
Stukenkemper T, Paquez X, Verhoeven MWGM, Hensen EJM, Dias AA, Brougham DF, Heise A. Polypeptide Polymer Brushes by Light-Induced Surface Polymerization of Amino Acid N
-Carboxyanhydrides. Macromol Rapid Commun 2018; 39:e1700743. [DOI: 10.1002/marc.201700743] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 12/08/2017] [Indexed: 01/03/2023]
|
133
|
Chen W, Zijlstra B, Filot IAW, Pestman R, Hensen EJM. Front Cover: Mechanism of Carbon Monoxide Dissociation on a Cobalt Fischer-Tropsch Catalyst (ChemCatChem 1/2018). ChemCatChem 2018. [DOI: 10.1002/cctc.201701929] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
134
|
Chen W, Zijlstra B, Filot IAW, Pestman R, Hensen EJM. Mechanism of Carbon Monoxide Dissociation on a Cobalt Fischer-Tropsch Catalyst. ChemCatChem 2018. [DOI: 10.1002/cctc.201701936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
135
|
Su YQ, Filot IAW, Liu JX, Hensen EJM. Stable Pd-Doped Ceria Structures for CH 4 Activation and CO Oxidation. ACS Catal 2018; 8:75-80. [PMID: 29333329 PMCID: PMC5762167 DOI: 10.1021/acscatal.7b03295] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 10/24/2017] [Indexed: 11/29/2022]
Abstract
![]()
Doping
CeO2 with Pd atoms has been associated with catalytic
CO oxidation, but current surface models do not allow CO adsorption.
Here, we report a new structure of Pd-doped CeO2(111),
in which Pd adopts a square planar configuration instead of the previously
assumed octahedral configuration. Oxygen removal from this doped structure
is favorable. The resulting defective Pd-doped CeO2 surface
is active for CO oxidation and is also able to cleave the first C–H
bond in methane. We show how the moderate CO adsorption energy and
dynamic features of the Pd atom upon CO adsorption and CO oxidation
contribute to a low-barrier catalytic cycle for CO oxidation. These
structures, which are also observed for Ni and Pt, can lead to a more
open coordination environment around the doped-transition-metal center.
These thermally stable structures are relevant to the development
of single-atom catalysts.
Collapse
|
136
|
Goryachev A, Gao L, van Veldhoven RPJ, Haverkort JEM, Hofmann JP, Hensen EJM. On the origin of the photocurrent of electrochemically passivated p-InP(100) photoelectrodes. Phys Chem Chem Phys 2018; 20:14242-14250. [DOI: 10.1039/c8cp00894a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The evaluation of faradaic efficiencies is essential to unambiguously determine the origin of photocurrents as showcased for electrochemically conditioned p-InP.
Collapse
|
137
|
Filonenko GA, van Putten R, Hensen EJM, Pidko EA. Catalytic (de)hydrogenation promoted by non-precious metals – Co, Fe and Mn: recent advances in an emerging field. Chem Soc Rev 2018; 47:1459-1483. [DOI: 10.1039/c7cs00334j] [Citation(s) in RCA: 406] [Impact Index Per Article: 67.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
This review is aimed at introducing the remarkable progress made in the last three years in the development of base metal catalysts for hydrogenations and dehydrogenative transformations.
Collapse
|
138
|
Liu C, Pidko EA, Hensen EJM. Origin of enhanced Brønsted acidity of NiF-modified synthetic mica–montmorillonite clay. Catal Sci Technol 2018. [DOI: 10.1039/c7cy02053h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The Brønsted acidity of synthetic mica–montmorillonite (SMM) clay was studied by periodic DFT calculations.
Collapse
|
139
|
Kosinov N, Wijpkema ASG, Uslamin E, Rohling R, Coumans FJAG, Mezari B, Parastaev A, Poryvaev AS, Fedin MV, Pidko EA, Hensen EJM. Confined Carbon Mediating Dehydroaromatization of Methane over Mo/ZSM-5. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201711098] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
140
|
Chen W, Pestman R, Zijlstra B, Filot IAW, Hensen EJM. Mechanism of Cobalt-Catalyzed CO Hydrogenation: 1. Methanation. ACS Catal 2017; 7:8050-8060. [PMID: 29226009 PMCID: PMC5716442 DOI: 10.1021/acscatal.7b02757] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 09/24/2017] [Indexed: 11/28/2022]
Abstract
![]()
The
mechanism of CO hydrogenation to CH4 at 260 °C
on a cobalt catalyst is investigated using steady-state isotopic transient
kinetic analysis (SSITKA) and backward and forward chemical transient
kinetic analysis (CTKA). The dependence of CHx residence time is determined by 12CO/H2 → 13CO/H2 SSITKA as a function of the
CO and H2 partial pressure and shows that the CH4 formation rate is mainly controlled by CHx hydrogenation rather than CO dissociation. Backward CO/H2 → H2 CTKA emphasizes the importance of
H coverage on the slow CHx hydrogenation
step. The H coverage strongly depends on the CO coverage, which is
directly related to CO partial pressure. Combining SSITKA and backward
CTKA allows determining that the amount of additional CH4 obtained during CTKA is nearly equal to the amount of CO adsorbed
to the cobalt surface. Thus, under the given conditions overall barrier
for CO hydrogenation to CH4 under methanation condition
is lower than the CO adsorption energy. Forward CTKA measurements
reveal that O hydrogenation to H2O is also a relatively
slow step compared to CO dissociation. The combined transient kinetic
data are used to fit an explicit microkinetic model for the methanation
reaction. The mechanism involving direct CO dissociation represents
the data better than a mechanism in which H-assisted CO dissociation
is assumed. Microkinetics simulations based on the fitted parameters
confirms that under methanation conditions the overall CO consumption
rate is mainly controlled by C hydrogenation and to a smaller degree
by O hydrogenation and CO dissociation. These simulations are also
used to explore the influence of CO and H2 partial pressure
on possible rate-controlling steps.
Collapse
|
141
|
Chen W, Filot IAW, Pestman R, Hensen EJM. Mechanism of Cobalt-Catalyzed CO Hydrogenation: 2. Fischer-Tropsch Synthesis. ACS Catal 2017; 7:8061-8071. [PMID: 29226010 PMCID: PMC5716444 DOI: 10.1021/acscatal.7b02758] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 09/24/2017] [Indexed: 11/28/2022]
Abstract
![]()
Fischer–Tropsch
(FT) synthesis is one of the most complex
catalyzed chemical reactions in which the chain-growth mechanism that
leads to formation of long-chain hydrocarbons is not well understood
yet. The present work provides deeper insight into the relation between
the kinetics of the FT reaction on a silica-supported cobalt catalyst
and the composition of the surface adsorbed layer. Cofeeding experiments
of 12C3H6 with 13CO/H2 evidence that CHx surface intermediates
are involved in chain growth and that chain growth is highly reversible.
We present a model-based approach of steady-state isotopic transient
kinetic analysis measurements at FT conditions involving hydrocarbon
products containing up to five carbon atoms. Our data show that the
rates of chain growth and chain decoupling are much higher than the
rates of monomer formation and chain termination. An important corollary
of the microkinetic model is that the fraction of free sites, which
is mainly determined by CO pressure, has opposing effects on CO consumption
rate and chain-growth probability. Lower CO pressure and more free
sites leads to increased CO consumption rate but decreased chain-growth
probability because of an increasing ratio of chain decoupling over
chain growth. The preferred FT condition involves high CO pressure
in which chain-growth probability is increased at the expense of the
CO consumption rate.
Collapse
|
142
|
Liu C, van Santen RA, Poursaeidesfahani A, Vlugt TJH, Pidko EA, Hensen EJM. Hydride Transfer versus Deprotonation Kinetics in the Isobutane-Propene Alkylation Reaction: A Computational Study. ACS Catal 2017; 7:8613-8627. [PMID: 29226012 PMCID: PMC5716443 DOI: 10.1021/acscatal.7b02877] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 11/01/2017] [Indexed: 12/04/2022]
Abstract
The alkylation of isobutane with light alkenes plays an essential role in modern petrochemical processes for the production of high-octane gasoline. In this study we have employed periodic DFT calculations combined with microkinetic simulations to investigate the complex reaction mechanism of isobutane-propene alkylation catalyzed by zeolitic solid acids. Particular emphasis was given to addressing the selectivity of the alkylate formation versus alkene formation, which requires a high rate of hydride transfer in comparison to the competitive oligomerization and deprotonation reactions resulting in catalyst deactivation. Our calculations reveal that hydride transfer from isobutane to a carbenium ion occurs via a concerted C-C bond formation between a tert-butyl fragment and an additional olefin, or via deprotonation of the tert-butyl fragment to generate isobutene. A combination of high isobutane concentration and low propene concentration at the reaction center favor the selective alkylation. The key reaction step that has to be suppressed to increase the catalyst lifetime is the deprotonation of carbenium intermediates that are part of the hydride transfer reaction cycle.
Collapse
|
143
|
Chen W, Zijlstra B, Filot IAW, Pestman R, Hensen EJM. Mechanism of Carbon Monoxide Dissociation on a Cobalt Fischer-Tropsch Catalyst. ChemCatChem 2017; 10:136-140. [PMID: 29399207 PMCID: PMC5768026 DOI: 10.1002/cctc.201701203] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 08/16/2017] [Indexed: 11/07/2022]
Abstract
The way in which the triple bond in CO dissociates, a key reaction step in the Fischer–Tropsch (FT) reaction, is a subject of intense debate. Direct CO dissociation on a Co catalyst was probed by 12C16O/13C18O scrambling in the absence and presence of H2. The initial scrambling rate without H2 was significantly higher than the rate of CO consumption under CO hydrogenation conditions, which indicated that the surface contained sites sufficiently reactive to dissociate CO without the assistance of H atoms. Only a small fraction of the surface was involved in CO scrambling. The minor influence of CO scrambling and CO residence time on the partial pressure of H2 showed that CO dissociation was not affected by the presence of H2. The positive H2 reaction order was correlated to the fact that the hydrogenation of adsorbed C and O atoms was slower than CO dissociation. Temperature‐programmed in situ IR spectroscopy underpinned the conclusion that CO dissociation does not require H atoms.
Collapse
|
144
|
Su YQ, Liu JX, Filot IAW, Hensen EJM. Theoretical Study of Ripening Mechanisms of Pd Clusters on Ceria. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2017; 29:9456-9462. [PMID: 29170602 PMCID: PMC5695895 DOI: 10.1021/acs.chemmater.7b03555] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 10/13/2017] [Indexed: 05/28/2023]
Abstract
We carried out density functional theory calculations to investigate the ripening of Pd clusters on CeO2(111). Starting from stable Pd n clusters (n = 1-21), we compared how these clusters can grow through Ostwald ripening and coalescence. As Pd atoms have mobility higher than that of Pd n clusters on the CeO2(111) surface, Ostwald ripening is predicted to be the dominant sintering mechanism. Particle coalescence is possible only for clusters with less than 5 Pd atoms. These ripening mechanisms are facilitated by adsorbed CO through lowering barriers for the cluster diffusion, detachment of a Pd atom from clusters, and transformation of initial planar clusters.
Collapse
|
145
|
Huang X, Atay C, Zhu J, Palstra SWL, Korányi TI, Boot MD, Hensen EJM. Catalytic Depolymerization of Lignin and Woody Biomass in Supercritical Ethanol: Influence of Reaction Temperature and Feedstock. ACS SUSTAINABLE CHEMISTRY & ENGINEERING 2017; 5:10864-10874. [PMID: 29142789 PMCID: PMC5678292 DOI: 10.1021/acssuschemeng.7b02790] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 09/27/2017] [Indexed: 05/21/2023]
Abstract
The one-step ethanolysis approach to upgrade lignin to monomeric aromatics using a CuMgAl mixed oxide catalyst is studied in detail. The influence of reaction temperature (200-420 °C) on the product distribution is investigated. At low temperature (200-250 °C), recondensation is dominant, while char-forming reactions become significant at high reaction temperature (>380 °C). At preferred intermediate temperatures (300-340 °C), char-forming reactions are effectively suppressed by alkylation and Guerbet and esterification reactions. This shifts the reaction toward depolymerization, explaining high monomeric aromatics yield. Carbon-14 dating analysis of the lignin residue revealed that a substantial amount of the carbon in the lignin residue originates from reactions of lignin with ethanol. Recycling tests show that the activity of the regenerated catalyst was strongly decreased due to a loss of basic sites due to hydrolysis of the MgO function and a loss of surface area due to spinel oxide formation of the Cu and Al components. The utility of this one-step approach for upgrading woody biomass was also demonstrated. An important observation is that conversion of the native lignin contained in the lignocellulosic matrix is much easier than the conversion of technical lignin.
Collapse
|
146
|
Obydenkova SV, Kouris PD, Hensen EJM, Heeres HJ, Boot MD. Environmental economics of lignin derived transport fuels. BIORESOURCE TECHNOLOGY 2017; 243:589-599. [PMID: 28709064 DOI: 10.1016/j.biortech.2017.06.157] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 06/27/2017] [Accepted: 06/28/2017] [Indexed: 06/07/2023]
Abstract
This paper explores the environmental and economic aspects of fast pyrolytic conversion of lignin, obtained from 2G ethanol plants, to transport fuels for both the marine and automotive markets. Various scenarios are explored, pertaining to aggregation of lignin from several sites, alternative energy carries to replace lignin, transport modalities, and allocation methodology. The results highlight two critical factors that ultimately determine the economic and/or environmental fuel viability. The first factor, the logistics scheme, exhibited the disadvantage of the centralized approach, owing to prohibitively expensive transportation costs of the low energy-dense lignin. Life cycle analysis (LCA) displayed the second critical factor related to alternative energy carrier selection. Natural gas (NG) chosen over additional biomass boosts well-to-wheel greenhouse gas emissions (WTW GHG) to a level incompatible with the reduction targets set by the U.S. renewable fuel standard (RFS). Adversely, the process' economics revealed higher profits vs. fossil energy carrier.
Collapse
|
147
|
Liu C, Tranca I, van Santen RA, Hensen EJM, Pidko EA. Scaling Relations for Acidity and Reactivity of Zeolites. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2017; 121:23520-23530. [PMID: 29142616 PMCID: PMC5677757 DOI: 10.1021/acs.jpcc.7b08176] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/02/2017] [Indexed: 05/22/2023]
Abstract
Zeolites are widely applied as solid acid catalysts in various technological processes. In this work we have computationally investigated how catalytic reactivity scales with acidity for a range of zeolites with different topologies and chemical compositions. We found that straightforward correlations are limited to zeolites with the same topology. The adsorption energies of bases such as carbon monoxide (CO), acetonitrile (CH3CN), ammonia (NH3), trimethylamine (N(CH3)3), and pyridine (C5H5N) give the same trend of acid strength for FAU zeolites with varying composition. Crystal orbital Hamilton populations (COHP) analysis provides a detailed molecular orbital picture of adsorbed base molecules on the Brønsted acid sites (BAS). Bonding is dominated by strong σ donation from guest molecules to the BAS for the adsorbed CO and CH3CN complexes. An electronic descriptor of acid strength is constructed based on the bond order calculations, which is an intrinsic parameter rather than adsorption energy that contains additional contributions due to secondary effects such as van der Waals interactions with the zeolite walls. The bond order parameter derived for the CH3CN adsorption complex represents a useful descriptor for the intrinsic acid strength of FAU zeolites. For FAU zeolites the activation energy for the conversion of π-adsorbed isobutene into alkoxy species correlates well with the acid strength determined by the NH3 adsorption energies. Other zeolites such as MFI and CHA do not follow the scaling relations obtained for FAU; we ascribe this to the different van der Waals interactions and steric effects induced by zeolite framework topology.
Collapse
|
148
|
Vogiatzis KD, Li G, Hensen EJM, Gagliardi L, Pidko EA. Electronic Structure of the [Cu 3(μ-O) 3] 2+ Cluster in Mordenite Zeolite and Its Effects on the Methane to Methanol Oxidation. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2017; 121:22295-22302. [PMID: 29051794 PMCID: PMC5641944 DOI: 10.1021/acs.jpcc.7b08714] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Indexed: 05/25/2023]
Abstract
Identifying Cu-exchanged zeolites able to activate C-H bonds and selectively convert methane to methanol is a challenge in the field of biomimetic heterogeneous catalysis. Recent experiments point to the importance of trinuclear [Cu3(μ-O)3]2+ complexes inside the micropores of mordenite (MOR) zeolite for selective oxo-functionalization of methane. The electronic structures of these species, namely, the oxidation state of Cu ions and the reactive character of the oxygen centers, are not yet fully understood. In this study, we performed a detailed analysis of the electronic structure of the [Cu3(μ-O)3]2+ site using multiconfigurational wave-function-based methods and density functional theory. The calculations reveal that all Cu sites in the cluster are predominantly present in the Cu(II) formal oxidation state with a minor contribution from Cu(III), whereas two out of three oxygen anions possess a radical character. These electronic properties, along with the high accessibility of the out-of-plane oxygen center, make this oxygen the preferred site for the homolytic C-H activation of methane by [Cu3(μ-O)3]2+. These new insights aid in the construction of a theoretical framework for the design of novel catalysts for oxyfunctionalization of natural gas and suggest further spectroscopic examination.
Collapse
|
149
|
Spezzati G, Su Y, Hofmann JP, Benavidez AD, DeLaRiva AT, McCabe J, Datye AK, Hensen EJM. Atomically Dispersed Pd-O Species on CeO 2(111) as Highly Active Sites for Low-Temperature CO Oxidation. ACS Catal 2017; 7:6887-6891. [PMID: 29034121 PMCID: PMC5634748 DOI: 10.1021/acscatal.7b02001] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 09/06/2017] [Indexed: 11/29/2022]
Abstract
![]()
Ceria-supported Pd
is a promising heterogeneous catalyst for CO
oxidation relevant to environmental cleanup reactions. Pd loaded onto
a nanorod form of ceria exposing predominantly (111) facets is already
active at 50 °C. Here we report a combination of CO-FTIR spectroscopy
and theoretical calculations that allows assigning different forms
of Pd on the CeO2(111) surface during reaction conditions.
Single Pd atoms stabilized in the form of PdO and PdO2 in
a CO/O2 atmosphere participate in a catalytic cycle involving
very low activation barriers for CO oxidation. The presence of single
Pd atoms on the Pd/CeO2-nanorod, corroborated by aberration-corrected
TEM and CO-FTIR spectroscopy, is considered pivotal to its high CO
oxidation activity.
Collapse
|
150
|
Zhu X, Kosinov N, Kubarev AV, Bolshakov A, Mezari B, Valastyan I, Hofmann JP, Roeffaers MBJ, Sarkadi-Pribóczki E, Hensen EJM. Cover Feature: Probing the Influence of SSZ-13 Zeolite Pore Hierarchy in Methanol-to-Olefins Catalysis by Using Nanometer Accuracy by Stochastic Chemical Reactions Fluorescence Microscopy and Positron Emission Profiling (ChemCatChem 18/2017). ChemCatChem 2017. [DOI: 10.1002/cctc.201701447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|