Heterogeneous Catalyst Deactivation and Regeneration: a Review
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Catalytic Transfer Hydrogenolysis Reactions for Lignin Valorization to Fuels and Chemicals
catalysts Review Catalytic Transfer Hydrogenolysis Reactions for Lignin Valorization to Fuels and Chemicals Antigoni Margellou 1 and Konstantinos S. Triantafyllidis 1,2,* 1 Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; [email protected] 2 Chemical Process and Energy Resources Institute, Centre for Research and Technology Hellas, 57001 Thessaloniki, Greece * Correspondence: [email protected] Received: 31 October 2018; Accepted: 10 December 2018; Published: 4 January 2019 Abstract: Lignocellulosic biomass is an abundant renewable source of chemicals and fuels. Lignin, one of biomass main structural components being widely available as by-product in the pulp and paper industry and in the process of second generation bioethanol, can provide phenolic and aromatic compounds that can be utilized for the manufacture of a wide variety of polymers, fuels, and other high added value products. The effective depolymerisation of lignin into its primary building blocks remains a challenge with regard to conversion degree and monomers selectivity and stability. This review article focuses on the state of the art in the liquid phase reductive depolymerisation of lignin under relatively mild conditions via catalytic hydrogenolysis/hydrogenation reactions, discussing the effect of lignin type/origin, hydrogen donor solvents, and related transfer hydrogenation or reforming pathways, catalysts, and reaction conditions. Keywords: lignin; catalytic transfer hydrogenation; hydrogenolysis; liquid phase reductive depolymerization; hydrogen donors; phenolic and aromatic compounds 1. Introduction The projected depletion of fossil fuels and the deterioration of environment by their intensive use has fostered research and development efforts towards utilization of alternative sources of energy. Biomass from non-edible crops and agriculture/forestry wastes or by-products is considered as a promising feedstock for the replacement of petroleum, coal, and natural gas in the production of chemicals and fuels. -
Enzyme Activity and Assays Introductory Article
Enzyme Activity and Assays Introductory article Robert K Scopes, La Trobe University, Bundoora, Victoria, Australia Article Contents . Factors that Affect Enzymatic Analysis Enzyme activity refers to the general catalytic properties of an enzyme, and enzyme assays . Initial Rates and Steady State Turnover are standardized procedures for measuring the amounts of specific enzymes in a sample. Measurement of Enzyme Activity . Measurement of Protein Concentration Factors that Affect Enzymatic Analysis . Methods for Purifying Enzymes . Summary Enzyme activity is measured in vitro under conditions that often do not closely resemble those in vivo. The objective of measuring enzyme activity is normally to determine the exactly what the concentration is (some preparations of amount of enzyme present under defined conditions, so unusual substrates may be impure, or the exact amount that activity can be compared between one sample and present may not be known). This is because the rate another, and between one laboratory and another. The measured varies with substrate concentration more rapidly conditions chosen are usually at the optimum pH, as the substrate concentration decreases, as can be seen in ‘saturating’ substrate concentrations, and at a temperature Figure 1. In most cases an enzyme assay has already been that is convenient to control. In many cases the activity is established, and the substrate concentration, buffers and measured in the opposite direction to that of the enzyme’s other parameters used previously should be used again. natural function. Nevertheless, with a complete study of There are many enzymes which do not obey the simple the parameters that affect enzyme activity it should be Michaelis–Menten formula. -
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. -
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.................................................. -
Surface Reactions and Chemical Bonding in Heterogeneous Catalysis
Surface reactions and chemical bonding in heterogeneous catalysis Henrik Öberg Doctoral Thesis in Chemical Physics at Stockholm University 2014 Thesis for the Degree of Doctor of Philosophy in Chemical Physics Department of Physics Stockholm University Stockholm 2014 c Henrik Oberg¨ ISBN 978-91-7447-893-8 Abstract This thesis summarizes studies which focus on addressing, using both theoretical and experimental methods, fundamental questions about surface phenomena, such as chemical reactions and bonding, related to processes in heterogeneous catalysis. The main focus is on the theoretical approach and this aspect of the results. The included articles are collected into three categories of which the first contains detailed studies of model systems in heterogeneous catalysis. For example, the trimerization of acetylene adsorbed on Cu(110) is measured using vibrational spectroscopy and modeled within the framework of Density Functional Theory (DFT) and quantitative agreement of the reaction barriers is obtained. In the second category, aspects of fuel cell catalysis are discussed. O2 dissociation is rate-limiting for the reduction of oxygen (ORR) under certain conditions and we find that adsorbate-adsorbate interactions are decisive when modeling this reaction step. Oxidation of Pt(111) (Pt is the electrocatalyst), which may alter the overall activity of the catalyst, is found to start via a PtO-like surface oxide while formation of a-PtO2 trilayers precedes bulk oxidation. When considering alternative catalyst materials for the ORR, their stability needs to be investigated in detail under realistic conditions. The Pt/Cu(111) skin alloy offers a promising candidate but segregation of Cu atoms to the surface is induced by O adsorption. -
Appendix H EPA Hazardous Waste Law
Appendix H EPA Hazardous Waste Law This Appendix is intended to give you background information on hazardous waste laws and how they apply to you. For most U.S. Environmental Protection Agency (EPA) requirements that apply to the University, the Safety Department maintains compliance through internal inspections, record keeping and proper disposal. In Wisconsin, the Department of Natural Resources (DNR) has adopted the EPA regulations, consequently EPA and DNR regulations are nearly identical. EPA defines This Appendix only deals with "hazardous waste" as defined by the EPA. hazardous waste as Legally, EPA defines hazardous waste as certain hazardous chemical waste. This hazardous chemical Appendix does not address other types of regulated laboratory wastes, such as waste; radioactive, infectious, biological, radioactive or sharps. Chapter 8 descibes disposal procedures infectious and biohazardous waste for animals. Chapter 9 describes disposal procedures for sharps and other waste that are regulated by can puncture tissue. Chapter 11 discusses Radiation and the Radiation Safety for other agencies. Radiation Workers provides guidelines for the disposal of radioactive waste. Procedures for medical waste are written by the UW Hospital Safety Officer. The Office of Biological Safety can provide guidance for the disposal of infectious and biological waste. EPA regulations focus on industrial waste streams. As a result, many laboratory chemical wastes are not regulated by EPA as hazardous chemical waste. However, many unregulated chemical wastes do merit special handling and disposal If a waste can be procedures. Thus, Chapter 7 and Appendix A of this Guide recommend disposal defined as: procedures for many unregulated wastes as if they were EPA hazardous waste. -
Update to the Developments of Hisarna an Ulcos Alternative Ironmaking Process Ir
Update to the Developments of Hisarna An Ulcos alternative ironmaking process Ir. Jan van der Stel , ir. Koen Meijer, ing. Cornelis Teerhuis, dr. Christiaan Zeijlstra, ir. Guus Keilman and ing. Maarten Ouwehand Tata Steel IJmuiden, The Netherlands Research, Development & Technology IEAGHG/IETS Iron and steel Industry CCUS and Process Integration Workshop Tokyo, Japan 4 – 7 November 2013 Confidential Content 1. HIsarna technology 2. HIsarna and CCS 3. HIsarna pilot plant 4. Campaign results 5. Conclusions 6. Forward plan 2 IEAGHG/IETS Iron and steel Industry CCUS and Process Integration Workshop , Tokyo, Japan, 4 – 7 November 2013. Confidential Ulcos IEAGHG/IETS Iron and steel Industry CCUS and Process Integration Workshop , Tokyo, Japan, 4 – 7 November 2013. Confidential 1. HIsarna technology Comparison with the BF route Blast furnace sinter Iron ore coke Liquid iron coal 4 IEAGHG/IETS Iron and steel Industry CCUS and Process Integration Workshop , Tokyo, Japan, 4 – 7 November 2013. Confidential 1. HIsarna technology Comparison with the BF route Blast furnace sinter Iron ore coke coal Direct use of coal and ore Liquid iron No coking and agglomeration 5 IEAGHG/IETS Iron and steel Industry CCUS and Process Integration Workshop , Tokyo, Japan, 4 – 7 November 2013. Confidential 1. HIsarna technology Top gas Oxygen Ore Oxygen Coal Slag Hot metal 6 IEAGHG/IETS Iron and steel Industry CCUS and Process Integration Workshop , Tokyo, Japan, 4 – 7 November 2013. Confidential 1.1. HIsarna technology Melting cyclone technology Melting and partial reduction of fine iron ores “2 Fe 2O3(s) + 2 CO(g) → 4 FeO(l) + 2 CO 2(g) ” • The cyclone product is a molten mixture of Fe 3O4 and FeO (~ 20 % reduced) • Pure oxygen is injected to generate the required melting temperature • The fines are separated from the gas by centrifugal flow of the gas IEAGHG/IETS Iron and steel Industry CCUS and Process Integration Workshop , Tokyo, Japan, 4 – 7 November 2013. -
Ultra Small-Mass AMS C Sample Preparation and Analyses At
NIM B Beam Interactions with Materials & Atoms Nuclear Instruments and Methods in Physics Research B 259 (2007) 293–302 www.elsevier.com/locate/nimb Ultra small-mass AMS 14C sample preparation and analyses at KCCAMS/UCI Facility G.M. Santos *, J.R. Southon, S. Griffin, S.R. Beaupre, E.R.M. Druffel Earth System Science, University of California, Irvine, B321 Croul Hall, Irvine, CA 92697-3100, USA Available online 31 January 2007 Abstract We have developed techniques for accurately and precisely measuring samples containing less than a few hundred micrograms of car- bon, using a compact AMS system (NEC 0.5 MV 1.5SDH-1). Detailed discussions of the sample preparation, measurement setup, data analysis and background corrections for a variety of standard samples ranging from 0.002 to 1 mgC are reported. Multiple aliquots of small amounts of CO2 were reduced to graphite with H2 over pre-baked iron powder catalyst. A reduction reaction temperature of 450 °C was adopted for graphite samples below 0.05 mgC, rather than the usual 550 °C used on samples of 0.1–1 mgC. In our regular reactors (3.1 cm3), this reduction in temperature improved the graphite yield from 60 to 90–100% for samples ranging from 0.006– 0.02 mgC. The combination of lower reaction temperature with a reduced reactor volume (1.6 cm3) gave yields as high as 100% on graphite samples <0.006 mgC. High performance measurements on ultra-small samples are possible also due to a modified NEC MC-SNIC ion-source that generates CÀ currents of 1 lA per lg of carbon for samples in the 0.002 to 0.010 mgC range, combined with on-line measurement of 12C and 13C (AMS d13C) to correct machine-induced isotopic fractionation. -
Nickel Carbonyl Final AEGL Document
Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 6 Committee on Acute Exposure Guideline Levels, Committee on Toxicology, National Research Council ISBN: 0-309-11214-1, 318 pages, 6 x 9, (2007) This free PDF was downloaded from: http://www.nap.edu/catalog/12018.html Visit the National Academies Press online, the authoritative source for all books from the National Academy of Sciences, the National Academy of Engineering, the Institute of Medicine, and the National Research Council: • Download hundreds of free books in PDF • Read thousands of books online, free • Sign up to be notified when new books are published • Purchase printed books • Purchase PDFs • Explore with our innovative research tools Thank you for downloading this free PDF. If you have comments, questions or just want more information about the books published by the National Academies Press, you may contact our customer service department toll-free at 888-624-8373, visit us online, or send an email to [email protected]. This free book plus thousands more books are available at http://www.nap.edu. Copyright © National Academy of Sciences. Permission is granted for this material to be shared for noncommercial, educational purposes, provided that this notice appears on the reproduced materials, the Web address of the online, full authoritative version is retained, and copies are not altered. To disseminate otherwise or to republish requires written permission from the National Academies Press. Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 6 http://www.nap.edu/catalog/12018.html Committee on Acute Exposure Guideline Levels Committee on Toxicology Board on Environmental Studies and Toxicology Copyright © National Academy of Sciences. -
Surface Models in Heterogeneous Catalysis the Synthesis of Ammonia and the Conversion of Carbon Monoxide
JOURNAL OF CATALYSIS 8, 29-35 (1967) Surface Models in Heterogeneous Catalysis The Synthesis of Ammonia and the Conversion of Carbon Monoxide G. PARRAVANO From the Deparzment qf Chemical and Metallurgical Engineering, University qf Michigan Ann Arbor, Machigan Received November 16, 1966, revised January 16, 1967 The establishment of chemical equilibria between gas and solid catalysts during the synthesis of NH3 and the conversion of CO is considered. Suitable solid-gas equilibrium reactions are discussed. With the correct choice of the rate-controlling step, the equilib- rium surface models are able to reproduce the experimental expressions for the rates of reaction. These models represent a drastic departure from the concept of a fixed, hetero- geneous surface that has been extensively used in the past for the interpretation of the experimental results on the above reactions. The two approaches, however, complement each other and the validity of each one may well be justified under different experimental conditions. Thus, a model may be considered the extension of the other by modification of some of the parameters of the system. Over the past several years many investi- view and it is certainly invalid for relatively gations have been carried out on the catalytic long periods of catalyst operation. It is, synthesis of NH3 and on the conversion of therefore, of interest to consider other CO. The studies have generally been directed possibilities more physically justifiable. toward the understanding of the nature, In this direction it seems particularly properties, and operation of the catalytic important to consider the possibility that surface through the analysis of experimental equilibration reactions between surface and results of reaction rates. -
Ignition Characteristics of Heptane-Hydrogen and Heptane
international journal of hydrogen energy 36 (2011) 15392e15402 Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he Ignition characteristics of heptaneehydrogen and heptaneemethane fuel blends at elevated pressures S.K. Aggarwal*, O. Awomolo, K. Akber Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 W, Taylor St, Chicago, IL 60607, USA article info abstract Article history: There is significant interest in using hydrogen and natural gas for enhancing the perfor- Received 20 May 2011 mance of diesel engines. We report herein a numerical investigation on the ignition of Received in revised form n-C7H16/H2 and n-C7H16/CH4 fuel blends. The CHEMKIN 4.1 software is used to model 17 August 2011 ignition in a closed homogenous reactor under conditions relevant to diesel/HCCI engines. Accepted 19 August 2011 Three reaction mechanisms used are (i) NIST mechanism involving 203 species and 1463 Available online 14 September 2011 reactions, (ii) Dryer mechanism with 116 species and 754 reactions, and (iii) a reduced mechanism (Chalmers) with 42 species and 168 reactions. The parameters include pres- Keywords: sures of 30 atm and 55 atm, equivalence ratios of ɸ ¼ 0.5, 1.0 and 2.0, temperature range of e Hydrogeneheptane blends 800 1400 K, and mole fractions of H2 or CH4 in the blend between 0 and 100%. For Methaneeheptane blends n-C7H16/air mixtures, the Chalmers mechanism not only provides closer agreement with Ignition measurements compared to the other two mechanisms, but also reproduces the negative Engine conditions temperature coefficient regime. Consequently, this mechanism is used to characterize the effects of H2 or CH4 on the ignition of n-C7H16. -
Organic Chemistry Name Formula Isomers Methane CH 1 Ethane C H
Organic Chemistry Organic chemistry is the chemistry of carbon. The simplest carbon molecules are compounds of just carbon and hydrogen, hydrocarbons. We name the compounds based on the length of the longest carbon chain. We then add prefixes and suffixes to describe the types of bonds and any add-ons the molecule has. When the molecule has just single bonds we use the -ane suffix. Name Formula Isomers Methane CH4 1 Ethane C2H6 1 Propane C3H8 1 Butane C4H10 2 Pentane C5H12 3 Hexane C6H14 5 Heptane C7H16 9 Octane C8H18 18 Nonane C9H20 35 Decane C10H22 75 Isomers are compounds that have the same formula but different bonding. isobutane n-butane 1 Naming Alkanes Hydrocarbons are always named based on the longest carbon chain. When an alkane is a substituent group they are named using the -yl ending instead of the -ane ending. So, -CH3 would be a methyl group. The substituent groups are named by numbering the carbons on the longest chain so that the first branching gets the lowest number possible. The substituents are listed alphabetically with out regard to the number prefixes that might be used. 3-methylhexane 1 2 3 4 5 6 6 5 4 3 2 1 Alkenes and Alkynes When a hydrocarbon has a double bond we replace the -ane ending with -ene. When the hydrocarbon has more than three carbon the position of the double bond must be specified with a number. 1-butene 2-butene Hydrocarbons with triple bonds are named basically the same, we replace the -ane ending with -yne.