Conversion of Oxygenates from Biomass-Derived Compounds over Supported Metal Catalysts

The increasing consumption and phase-out of conventional fuels has caused the tremendous interest of our society in making use of renewable energy resources such as biomass. In response to this interest, bio-oil produced from biomass feed stocks has been gradually making its contribution as a part of normal fuels. However, since the bio-oil is not stable due to its high oxygen content, upgrading is necessary to improve its performance. Since the high oxygen content of bio-oils has limited its storage ability and lowered its heating content, in some cases, removing oxygen or deoxygenating bio-oil molecules has been proposed as a recommended catalytic reaction. However, the role of the bio-oil upgrading process is not only to eliminate oxygen, but also to retain carbon in the liquid, preferably by the cleavage of C-O bonds. In the scope of this dissertation, the author will present how a detailed knowledge of the nature of adsorbed species on different metal surfaces leads to tailored catalysts with the desired properties for conversion of oxygenates derived from bio-oils.In the first part of the dissertation, the author will focus on the deoxygenation reaction of furfural, which can be derived from biomass feed stocks and contain the aldehyde functional group, on different monometallic catalysts. Within this context, copper, palladium and nickel catalysts have been selected to study their activity, selectivity, and possible reaction pathways. The study of the behavior of different metals may be useful in designing catalytic strategies towards the production of fuel components with specific characteristics. For the second part of the dissertation, bimetallic alloy catalysts have been used for the conversion of furfural. In this regard, the product with minimal reduction of carbon yield has been achieved. For example, monometallic Pd catalyst is highly active for decarbonylation of furfural by C-C bond cleavage yielding furan and CO as the dominant product. However, the addition of Fe to Pd forming Pd-Fe alloy, making the C-O bond cleavage more favorable, can dramatically change the product selectivity from furan to 2-methylfuran

Hydrogenolysis of glycidol as an alternative route to obtain 1,3-propanediol selectively using MOx-modified nickel-copper catalysts supported on acid mesoporous saponite

Ni and Cu mono- and bimetallic catalysts modified with various types of acid oxides MOx (M=Mo, V, W, and Re) were tested for the hydrogenolysis of glycidol as an alternative route to the hydrogenolysis of glycerol to obtain 1,3-propanediol (1,3-PrD). Characterization results revealed that the presence of modifiers affected the dispersion and reducibility of the NiO particles and the strength and amount of acid sites. Among the modifiers tested, Re led to the highest activity, a high propanediols selectivity, and the highest 1,3-PrD/1,2-propanediol (1,2-PrD) ratio. The Ni-Cu/Re ratio was optimized to improve the catalytic activity. The best catalytic result, with a 46 % 1,3-PrD yield and a 1,3-PrD/1,2-PrD ratio of 1.24, was obtained if the monometallic Ni catalyst at 40 wt % loading and modified with 7 wt % Re was used at 393 K and 5 MPa H2 pressure after 4 h of reaction. The overall 1,3-PrD yield starting from glycerol and assuming a two-step synthesis (glycerol¿glycidol¿1,3-PrD) and a yield of 78 % for the first step would be 36 %. This 1,3-PD yield is the highest for a reaction catalyzed by a non-noble metal and is comparable to the direct hydrogenolysis of glycerol using noble metal catalysts at a longer time and a high H2 pressure.Peer ReviewedPostprint (author's final draft

Identification of active sites on supported metal catalysts with carbon nanotube hydrogen highways

Catalysts consisting of metal particles supported on reducible oxides exhibit promising activity and selectivity for a variety of current and emerging industrial processes. Enhanced catalytic activity can arise from direct contact between the support and the metal or from metal-induced promoter effects on the oxide. Discovering the source of enhanced catalytic activity and selectivity is challenging, with conflicting arguments often presented based on indirect evidence. Here, we separate the metal from the support by a controlled distance while maintaining the ability to promote defects via the use of carbon nanotube hydrogen highways. As illustrative cases, we use this approach to show that the selective transformation of furfural to methylfuran over Pd/TiO2 occurs at the Pd-TiO2 interface while anisole conversion to phenol and cresol over Cu/TiO2 is facilitated by exposed Ti3+ cations on the support. This approach can be used to clarify many conflicting arguments in the literatureWe acknowledge financial support from the National Science Foundation, Grant CAREER1653935. Use of the Advanced Photon Source is supported by the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences, under Contract DE-AC02-06CH11357. MRCAT operations are supported by the Department of Energy and the MRCAT member institutions. E.C.W. and J.T.M. were supported in part by Center for Innovative Transformation of Alkane Resources (CISTAR) by the National Science Foundation under Cooperative Agreement No. EEC-1647722. Open access fees fees for this article provided whole or in part by OU Libraries Open Access Fund.Ye

Conversion of biomass platform molecules into fuel additives and liquid hydrocarbon fuels

[EN] In this work some relevant processes for the preparation of liquid hydrocarbon fuels and fuel additives from cellulose, hemicellulose and triglycerides derived platform molecules are discussed. Thus, it is shown that a series of platform molecules such as levulinic acid, furans, fatty acids and polyols can be converted into a variety of fuel additives through catalytic transformations that include reduction, esterification, etherification, and acetalization reactions. Moreover, we will show that liquid hydrocarbon fuels can be obtained by combining oxygen removal processes (e.g. dehydration, hydrogenolysis, hydrogenation, decarbonylation/descarboxylation etc.) with the adjustment of the molecular weight via C C coupling reactions (e.g. aldol condensation, hydroxyalkylation, oligomerization, ketonization) of the reactive platform molecules.This work has been supported by the Spanish Government-MINECO through Consolider Ingenio 2010-Multicat and CTQ.-2011-27550, ITQ thanks the "Program Severo Ochoa" for financial support.Climent Olmedo, MJ.; Corma Canós, A.; Iborra Chornet, S. (2014). Conversion of biomass platform molecules into fuel additives and liquid hydrocarbon fuels. Green Chemistry. 16(2):516-547. https://doi.org/10.1039/c3gc41492bS51654716

Ni-based bimetallic heterogeneous catalysts for energy and environmental applications

Bimetallic catalysts have attracted extensive attention for a wide range of applications in energy production and environmental remediation due to their tunable chemical/physical properties. These properties are mainly governed by a number of parameters such as compositions of the bimetallic systems, their preparation method, and their morphostructure. In this regard, numerous efforts have been made to develop “designer” bimetallic catalysts with specific nanostructures and surface properties as a result of recent advances in the area of materials chemistry. The present review highlights a detailed overview of the development of nickel-based bimetallic catalysts for energy and environmental applications. Starting from a materials science perspective in order to obtain controlled morphologies and surface properties, with a focus on the fundamental understanding of these bimetallic systems to make a correlation with their catalytic behaviors, a detailed account is provided on the utilization of these systems in the catalytic reactions related to energy production and environmental remediation. We include the entire library of nickel-based bimetallic catalysts for both chemical and electrochemical processes such as catalytic reforming, dehydrogenation, hydrogenation, electrocatalysis and many other reactions

Effects of van der Waals density functional corrections on trends in furfural adsorption and hydrogenation on close-packed transition metal surfaces.

The hydrogenation of furfural to furfuryl alcohol on Pd(111), Cu(111) and Pt(111) is studied with both standard Density Functional Theory (DFT)-GGA functionals and with van der Waals-corrected density functionals. VdWDF functionals, including optPBE, optB88, optB86b, and Grimme's method, are used to optimize the adsorption configurations of furfural, furfuryl alcohol, and related intermediates resulting from hydrogenation of furfural, and the results are compared to corresponding values determined with GGA functionals, including PW91 and PBE. On Pd(111) and Pt(111), the adsorption geometries of the intermediates are not noticeably different between the two classes of functionals, while on Cu(111),modest changes are seen in both the perpendicular distance and the orientation of the aromatic ringwith respect to the planar surface. In general, the binding energies increase substantially inmagnitude as a result of van derWaals contributions on all metals. In contrast, however, dispersion effects on the kinetics of hydrogenation are relatively small. It is found that activation barriers are not significantly affected by the inclusion of dispersion effects, and a Brønsted–Evans–Polanyi relationship developed solely fromPW91 calculations on Pd(111) is capable of describing corresponding results on Cu(111) and Pt(111), even when the dispersion effects are included. Finally, the reaction energies and barriers derived from the dispersion-corrected and pure GGA calculations are used to plot simple potential energy profiles for furfural hydrogenation to furfuryl alcohol on the three considered metals, and an approximately constant downshift of the energetics due to the dispersion corrections is observed

Hydrodeoxygenation of Furfural Over Supported Metal Catalysts: A Comparative Study of Cu, Pd and Ni

Abstract The hydrodeoxygenation of furfural has been investigated over three different metal catalysts, Cu, Pd and Ni supported on SiO 2 , on a continuous-flow reactor under atmospheric pressure of hydrogen in the 210-290°C temperature range. The distribution of products is a strong function of the metal catalyst used. High selectivity to furfuryl alcohol is obtained over Cu/SiO 2 , with the formation of only small amounts of 2-methyl furan at the highest reaction temperature studied. In contrast to Cu catalyst, the conversion of furfural over Pd/SiO 2 mainly produces furan by decarbonylation. Furan can further react with hydrogen to form tetrahydrofuran (THF). Finally, on Ni/SiO 2 catalysts ring opening products (butanal, butanol and butane) can be obtained in significant amounts. The different product distributions are explained in terms of the strength of interaction of the furan ring with the metal surface and the type of surface intermediates that each metal is able to stabilize