Kinetics and Catalysis of the Water-Gas-Shift Reaction: a Microkinetic and Graph Theoretic Approach
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Zn-Al Mixed Oxides Decorated with Potassium As Catalysts for HT-WGS: Preparation and Properties
catalysts Article Zn-Al Mixed Oxides Decorated with Potassium as Catalysts for HT-WGS: Preparation and Properties Katarzyna Antoniak-Jurak * , Paweł Kowalik, Kamila Michalska, Wiesław Próchniak and Robert Bicki Łukasiewicz Research Network—New Chemical Syntheses Institute, Al. Tysi ˛acleciaPa´nstwa Polskiego 13A, 24-110 Puławy, Poland; [email protected] (P.K.); [email protected] (K.M.); [email protected] (W.P.); [email protected] (R.B.) * Correspondence: [email protected]; Tel.: +48-8-1473-1754 Received: 8 September 2020; Accepted: 18 September 2020; Published: 21 September 2020 Abstract: A set of ex-ZnAl-LDHs catalysts with a molar ratio of Zn/Al in the range of 0.3–1.0 was prepared using co-precipitation and thermal treatment. The samples were characterized using various methods, including X-ray fluorescence spectroscopy (XRF), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy FT-IR, N2 adsorption, Temperature-programmed desorption of CO2 (TPD-CO2) as well as Scanning electron microscopy (SEM-EDS). Catalyst activity and long-term stability measurements were carried out in a high-temperature water–gas shift (HT-WGS) reaction. Mixed oxide catalysts with various Zn/Al molar ratios decorated with potassium showed high activity in the HT-WGS reaction within the temperature range of 330–400 ◦C. The highest activity was found for the Zn/Al molar ratio of 0.5 corresponding to spinel stoichiometry. However, the catalyst with a stoichiometric spinel molar ratio of Zn/Al (ZnAl_0.5_K) revealed a higher tendency for surface migration and/or vaporization of potassium during overheating at 450 ◦C. -
Steam Reforming of Lower Alkanes and the Water-Gas Shift Reaction
INVESTIGATION OF ACTIVE SITES AND REACTION NETWORKS IN CATALYTIC HYDROGEN PRODUCTION: STEAM REFORMING OF LOWER ALKANES AND THE WATER-GAS SHIFT REACTION DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Sittichai Natesakhawat, M.S. * * * * * The Ohio State University 2005 Dissertation Committee: Approved by Professor Umit S. Ozkan, Adviser Professor Jeffrey J. Chalmers Professor David L. Tomasko _________________________ Professor Heather Davis Adviser Graduate Program in Chemical Engineering ABSTRACT Steam reforming (SR) of hydrocarbons and water-gas shift (WGS) are of importance in hydrogen generation technologies due to recent attention focusing on fuel cells. Current research efforts have focused on catalyst development to improve activity, selectivity, and stability under a realistic range of operating conditions. Although coke formation is a major concern for Ni-based catalysts when used for hydrocarbon steam reforming, their low cost and long-proven performance warrants further investigation. Moreover, hydrogen and fuel cell technologies will greatly benefit from innovative high- temperature shift (HTS) catalyst formulations that can overcome some serious drawbacks (i.e., low activity at low temperatures, sintering of magnetite (Fe3O4), a pyrophoric nature, and the harmful effects of Cr6+ on human health). In this Ph.D. study, lanthanide-promoted Ni/Al2O3 catalysts and Fe-based catalysts promoted with first row transition metals were synthesized by a modified sol-gel technique and a coprecipitation method, respectively. The effect of synthesis variables on the catalyst properties (i.e., BET surface area, reducibility, crystallite size, crystal structure, oxidation states, adsorption/desorption behavior, and surface intermediates during the reaction) and, in turn, on the catalytic performance in SR of lower alkanes and ii the WGS reaction has been investigated. -
Opportunities for Catalysis in the 21St Century
Opportunities for Catalysis in The 21st Century A Report from the Basic Energy Sciences Advisory Committee BASIC ENERGY SCIENCES ADVISORY COMMITTEE SUBPANEL WORKSHOP REPORT Opportunities for Catalysis in the 21st Century May 14-16, 2002 Workshop Chair Professor J. M. White University of Texas Writing Group Chair Professor John Bercaw California Institute of Technology This page is intentionally left blank. Contents Executive Summary........................................................................................... v A Grand Challenge....................................................................................................... v The Present Opportunity .............................................................................................. v The Importance of Catalysis Science to DOE.............................................................. vi A Recommendation for Increased Federal Investment in Catalysis Research............. vi I. Introduction................................................................................................ 1 A. Background, Structure, and Organization of the Workshop .................................. 1 B. Recent Advances in Experimental and Theoretical Methods ................................ 1 C. The Grand Challenge ............................................................................................. 2 D. Enabling Approaches for Progress in Catalysis ..................................................... 3 E. Consensus Observations and Recommendations.................................................. -
'New Insights on the Selective Oxidation of Methanol to Formaldehyde on Femo Based Catalysts'
‘New Insights on the Selective Oxidation of Methanol to Formaldehyde on FeMo Based Catalysts' Catherine Brookes School of Chemistry Cardiff University Thesis for the degree of Doctor of Philosophy i This thesis was submitted for examination in August 2015. ii Abstract The selective oxidation of methanol has been studied in detail, with particular focus on gaining insights into the surface active sights responsible for directing the selectivity to formaldehyde. Various Fe and Mo containing oxides have been investigated for their reactivity with methanol, to gain an understanding of the different roles of these components in the industrial catalyst employed, which is a mixed phase comprised of MoO 3 and Fe 2(MoO 4)3. Catalysts have primarily been tested through using TPD (temperature programmed desorption) and TPPFR (temperature programmed pulsed flow reaction). The reactivity of Fe 2O3 is dominated by combustion products, with CO 2 and H 2 produced via a formate intermediate adsorbing at the catalyst surface. For MoO 3 however, the surface is populated by methoxy intermediates, so that the selectivity is almost 100 % directed to formaldehyde. When a mixture of isolated Fe and Mo sites co-exist, the surface methoxy becomes stabilised, resulting in a dehydrogenation reaction to CO and H 2. CO and CO 2 can also be observed on Mo rich surfaces, however here a consequence of the further oxidation of formaldehyde, through a linear pathway. TPD and DRIFTS identify these intermediates and products forming. Since the structure of the industrial catalyst is relatively complex, in that it contains both MoO 3 and Fe 2(MoO 4)3, it is difficult to identify the active site for the reaction with methanol. -
Direct Synthesis of Dimethyl Ether from Syngas on Bifunctional Hybrid
catalysts Article Direct Synthesis of Dimethyl Ether from Syngas on Bifunctional Hybrid Catalysts Based on Supported H3PW12O40 and Cu-ZnO(Al): Effect of Heteropolyacid Loading on Hybrid Structure and Catalytic Activity Elena Millán , Noelia Mota, Rut Guil-López, Bárbara Pawelec , José L. García Fierro and Rufino M. Navarro * Instituto de Catálisis y Petroleoquímica (CSIC), C/Marie Curie 2, Cantoblanco, 28049 Madrid, Spain; [email protected] (E.M.); [email protected] (N.M.); [email protected] (R.G.-L.); [email protected] (B.P.); jlgfi[email protected] (J.L.G.F.) * Correspondence: [email protected] Received: 27 August 2020; Accepted: 15 September 2020; Published: 17 September 2020 Abstract: The performance of bifunctional hybrid catalysts based on phosphotungstic acid (H3PW12O40, HPW) supported on TiO2 combined with Cu-ZnO(Al) catalyst in the direct synthesis of dimethyl ether (DME) from syngas has been investigated. We studied the effect of the HPW loading on TiO2 (from 1.4 to 2.7 monolayers) on the dispersion and acid characteristics of the HPW clusters. When the concentration of the heteropoliacid is slightly higher than the monolayer (1.4 monolayers) the acidity of the clusters is perturbed by the surface of titania, while for concentration higher than 1.7 monolayers results in the formation of three-dimensional HPW nanocrystals with acidity similar to the bulk heteropolyacid. Physical hybridization of supported heteropolyacids with the Cu-ZnO(Al) catalyst modifies both the acid characteristics of the supported heteropolyacids and the copper surface area of the Cu-ZnO(Al) catalyst. -
Platinum Metals Industrial Catalysts Catalysis of Organic Reactions EDITED by M
Platinum Metals Industrial Catalysts Catalysis of Organic Reactions EDITED BY M. G. SCAROS AND M. L. PRUNIER, Marcel Dekker, New York, 1995, 599 pages, ISBN 0-8247-9364-1, U.S. $195.00 This book comprises a set of papers presented reactant purity, agitation and poisons are at the 15th Conference on Catalysis of Organic considered. This is followed by a paper detail- Reactions, held in Phoenix, Arizona, in May ing noble metal recovery operations and the var- 1994. It covers a variety of topics, such as het- ious steps involved in the noble metal “loop”. erogeneous catalysis, asymmetric hydrogena- Heterogeneous catalysis in organic synthesis tion, hydrogenation, oxidation, hydroformyla- is discussed by R. L. Augustine and colleagues tion, catalyst design and catalyst characterisation. from Seton Hall University, New Jersey. This One topic which is emphasised is hydrogena- is illustrated by the platinum catalysed oxida- tion (alpha to omega), and this is intended to tion of alcohols, carbon-carbon bond forming allow a better understanding of the entire reactions of supported palladium catalysts for process, from choosing a catalyst to the noble the Heck type arylation of allylic groups, and metal “loop”. There are over 60 papers and 186 by enantioselective heterogeneous catalysis, contributors, with a healthy number of these which includes the hydrogenation of a-ketoesters being from industry. A large proportion of the to chiral a-hydroxyesters using chinchona alka- papers deal with reactions involving platinum loid modified platinum catalysts. group metal catalysts, reflecting their impor- A detailed study of the homogeneously pal- tance to both academia and industry. -
The Unique Interplay Between Copper and Zinc During Catalytic Carbon Dioxide Hydrogenation to Methanol ✉ Maxim Zabilskiy 1 , Vitaly L
ARTICLE https://doi.org/10.1038/s41467-020-16342-1 OPEN The unique interplay between copper and zinc during catalytic carbon dioxide hydrogenation to methanol ✉ Maxim Zabilskiy 1 , Vitaly L. Sushkevich1, Dennis Palagin 1, Mark A. Newton2, Frank Krumeich 2 & ✉ Jeroen A. van Bokhoven 1,2 fi 1234567890():,; In spite of numerous works in the eld of chemical valorization of carbon dioxide into methanol, the nature of high activity of Cu/ZnO catalysts, including the reaction mechanism and the structure of the catalyst active site, remains the subject of intensive debate. By using high-pressure operando techniques: steady-state isotope transient kinetic analysis coupled with infrared spectroscopy, together with time-resolved X-ray absorption spectroscopy and X-ray powder diffraction, and supported by electron microscopy and theoretical modeling, we present direct evidence that zinc formate is the principal observable reactive intermediate, which in the presence of hydrogen converts into methanol. Our results indicate that the copper–zinc alloy undergoes oxidation under reaction conditions into zinc formate, zinc oxide and metallic copper. The intimate contact between zinc and copper phases facilitates zinc formate formation and its hydrogenation by hydrogen to methanol. 1 Laboratory for Catalysis and Sustainable Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland. 2 Institute for Chemistry and Bioengineering, ETH ✉ Zurich, Vladimir-Prelog-Weg 1, 8093 Zürich, Switzerland. email: [email protected]; [email protected] NATURE COMMUNICATIONS | (2020) 11:2409 | https://doi.org/10.1038/s41467-020-16342-1 | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | https://doi.org/10.1038/s41467-020-16342-1 arbon dioxide is a principal anthropogenic pollutant, ris- catalyst for this highly important and industrially relevant Cing level of which has a detrimental effect on the envir- reaction. -
Heterogeneous Catalyst Deactivation and Regeneration: a Review
Catalysts 2015, 5, 145-269; doi:10.3390/catal5010145 OPEN ACCESS catalysts ISSN 2073-4344 www.mdpi.com/journal/catalysts Review Heterogeneous Catalyst Deactivation and Regeneration: A Review Morris D. Argyle and Calvin H. Bartholomew * Chemical Engineering Department, Brigham Young University, Provo, UT 84602, USA; E-Mail: [email protected] * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel: +1-801-422-4162, Fax: +1-801-422-0151. Academic Editor: Keith Hohn Received: 30 December 2013 / Accepted: 12 September 2014 / Published: 26 February 2015 Abstract: Deactivation of heterogeneous catalysts is a ubiquitous problem that causes loss of catalytic rate with time. This review on deactivation and regeneration of heterogeneous catalysts classifies deactivation by type (chemical, thermal, and mechanical) and by mechanism (poisoning, fouling, thermal degradation, vapor formation, vapor-solid and solid-solid reactions, and attrition/crushing). The key features and considerations for each of these deactivation types is reviewed in detail with reference to the latest literature reports in these areas. Two case studies on the deactivation mechanisms of catalysts used for cobalt Fischer-Tropsch and selective catalytic reduction are considered to provide additional depth in the topics of sintering, coking, poisoning, and fouling. Regeneration considerations and options are also briefly discussed for each deactivation mechanism. Keywords: heterogeneous catalysis; deactivation; regeneration 1. Introduction Catalyst deactivation, the loss over time of catalytic activity and/or selectivity, is a problem of great and continuing concern in the practice of industrial catalytic processes. Costs to industry for catalyst replacement and process shutdown total billions of dollars per year. Time scales for catalyst deactivation vary considerably; for example, in the case of cracking catalysts, catalyst mortality may be on the order of seconds, while in ammonia synthesis the iron catalyst may last for 5–10 years. -
High Temperature Water Gas Shift Catalysts: a Computer Modelling Study
High Temperature Water Gas Shift Catalysts: A Computer Modelling Study Sreelekha Benny Department of Chemistry University College London Johnson Matthey Technology Centre Thesis submitted for the degree of Doctor in Engineering March 2010 “It's our attitude at the beginning of a difficult undertaking which more than anything else will determine its successful outcome." William James (Father of American psychology) 2 Declaration ____________________________________________________________________ Declaration I, Sreelekha Benny confirm that the work presented in this thesis is the result of my own investigations and where information has been derived from other sources, this has been fully acknowledged. 3 Abstract ____________________________________________________________________ Abstract The high-temperature (HT) Water Gas Shift (WGS) reaction has considerable technological relevance for lowering CO content during the conversion of natural gas or liquid hydrocarbons to hydrogen. Conventional HT-WGS catalysts based on oxides of iron and chromium are well established industrially. However, it is crucial to remove any impurities present such as Cr6+, S or N during the catalytic process. In particular, Cr6+ is regarded as a Class I carcinogen and its presence is restricted by EU legislation. Even though Cr6+ is reduced during the catalytic process, caution must still be taken to eliminate any further impurities. Hence, it is desirable to identify alternative promoters and develop a Cr-free HT-WGS catalyst. This thesis presents results obtained using atomistic simulation techniques to investigate the effect of Cr3+ and possible alternative dopants in three important iron oxide materials, Hematite (α-Fe2O3), Maghemite (γ-Fe2O3) and Magnetite (Fe3O4). The starting point is to develop an understanding of the structural properties and distribution of Cr3+ on the bulk and surface material of hematite. -
Redox Catalysis for Environmental Applications
REDOX CATALYSIS FOR ENVIRONMENTAL APPLICATIONS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Preshit Vilas Gawade, M.S. Chemical Engineering Graduate Program ***** The Ohio State University 2012 Dissertation Committee: Umit S. Ozkan, Advisor Jeffrey J. Chalmers Kurt W. Koelling James Coe Copyright by Preshit Vilas Gawade 2012 ABSTRACT The presented work comprehends a broad spectrum of redox catalysis for various environmental applications, such as i) hydrogen production via water-gas shift reaction, ii) hydrogen purification for fuel cell applications and iii) catalytic after-treatment of lean-burn engines. This dissertation involves, but is not limited to catalyst development, reaction studies and catalyst characterization for the above-mentioned environmental applications, which can be summarized as follows. (i) Water-gas shift (WGS) remains an essential step in integrated gasification combined cycle (IGCC) for hydrogen production, as it forms a link between the gasification process and fuel cell operations. The current catalysts for WGS application are based on Fe-Cr and Cu/ZnO/Al2O3, as a high temperature (HT-WGS) and low temperature (LT-WGS) catalysts, respectively. This two-stage WGS process is a consequence of several operational drawbacks of the current catalyst formulations including Cr+6 being carcinogenic. Hence the presented WGS project has a two-fold purpose. First, Cr-free Fe-based catalyst development and second, Cu supported catalyst development for WGS that can be operated over a wide temperature range. In this dissertation, Cr- free Fe-Al-Cu catalyst prepared through “one-step” sol- gel method using propylene oxide as a gelation agent has been reported. -
Nanostructured Catalysts for Hydrogen Generation From
BESH2015 Sub-Nanometer Sized Clusters for Heterogeneous Catalysis Principal Investigator: Abhaya Datye Organization: University of New Mexico Program Scope Providing sustainable sources of energy, chemicals, and materials is one of the most important long-term issues facing society. Catalysis plays a central role in creating sustainable sources of energy through efficient transformations of hydrocarbon resources. Our quality of life depends on myriad products that involve a catalytic step at some point in their manufacture. It is widely accepted that chemical catalysis is a major economic driver in both the U.S. and world economies, with estimates as high as ~35% of the world’s gross domestic product arising via catalytic processes. Due to this significant commercial impact, there is a heavy demand for rare and expensive transition metals whose pricing and availability is at risk due to increasing geopolitical pressures. As our resource base shifts to alternate energy sources such as natural gas or biomass, there will be a need to develop new catalysts for converting these materials. Our project focuses on sub-nanometer (nm) clusters, of size <30 atoms, which provide unusual reactivity and selectivity for catalytic reactions. The objective of our project is to improve methods to tailor surfaces of high surface area supports to anchor platinum group metals (PGM). Heterogeneous catalysis using nanoparticles of PGMs is highly developed, but the science of using ionic forms of these metals as heterogeneous catalysts is still in its infancy. New methods only recently available allow us to study these atomically dispersed metals. Catalysis using single isolated atoms provides the highest atom efficiency for conducting catalytic reactions. -
1 Introduction
1 1 Introduction 1.1 The Phenomenon Catalysis Catalysis is the key to chemical transformations. Most industrial syntheses and nearly all biological reactions require catalysts. Furthermore, catalysis is the most important technology in environmental protection, i. e., the prevention of emissions. A well-known example is the catalytic converter for automobiles. Catalytic reactions were already used in antiquity, although the underlying principle of catalysis was not recognized at the time. For example, the fermentation of sugar to ethanol and the conversion of ethanol to acetic acid are catalyzed by enzymes (biocata- lysts). However, the systematic scientific development of catalysis only began about 200 years ago, and its importance has grown up to the present day [2]. The term “catalysis” was introduced as early as 1836 by Berzelius in order to ex- plain various decomposition and transformation reactions. He assumed that catalysts possess special powers that can influence the affinity of chemical substances. A definition that is still valid today is due to Ostwald (1895): “a catalyst acceler- ates a chemical reaction without affecting the position of the equilibrium.” Ostwald recognized catalysis as a ubiquitous phenomenon that was to be explained in terms of the laws of physical chemistry. While it was formerly assumed that the catalyst remained unchanged in the course of the reaction, it is now known that the catalyst is involved in chemical bonding with the reactants during the catalytic process. Thus catalysis is a cyclic process: the reactants are bound to one form of the catalyst, and the products are released from another, regenerating the initial state.