Pavel Afanasiev

Bio: Pavel Afanasiev is an academic researcher from Claude Bernard University Lyon 1. The author has contributed to research in topics: Catalysis & Hydrodesulfurization. The author has an hindex of 40, co-authored 170 publications receiving 4926 citations. Previous affiliations of Pavel Afanasiev include University of Nantes & University of Lyon.

Hydrodeoxygenation of guaiacol with CoMo catalysts. Part I: Promoting effect of cobalt on HDO selectivity and activity

Abstract: Unsupported and alumina-supported MoS2 and CoMoS catalysts have been compared in the hydrodeoxygenation (HDO) reaction of guaiacol (2-methoxyphenol), a typical model molecule for bio-oils coming from the pyrolysis of ligno-cellulosic biomass. The goal of this work was to understand the cobalt promoting effect on MoS2 phase in this type of catalytic reaction. It appeared clearly that in the presence of the CoMoS phase, the direct deoxygenation (DDO) pathway involved in guaiacol conversion was strongly increased as compared to the non-promoted MoS2 in the bulk or supported state. This effect is similar to the well-known increase of direct desulfurization (DDS) pathway by cobalt promoter in the hydrodesulfurization (HDS) of refractory sulfur compounds over molybdenum sulfide catalysts.

Surfactant-assisted synthesis of highly dispersed molybdenum sulfide

Abstract: A simple preparation method of high surface area MoS2 using reactions in aqueous solution in the presence of an organic surfactant has been reported. Molybdenum sulfide was obtained from the reactions of aqueous (NH4)2MoS4 with N2H4 or NH2OH·H2SO4, followed by thermal treatment under nitrogen flow. The solids were characterized by X-ray diffraction, chemical analysis, surface and porosity measurements, photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HREM). Addition of the cetyltrimetylammonium chloride surfactant to the reaction mixtures led to the increase of specific surface area up to 210 m2/g and disappearance of MoS2 layers stacking. Single layer, short fringes of MoS2 were observed by HREM. The solids contained 4−8 wt % of carbon impurity, which probably acts as a textural stabilizer.

The Catalytic Valorization of Lignin for the Production of Renewable Chemicals

Abstract: Biomass is an important feedstock for the renewable production of fuels, chemicals, and energy. As of 2005, over 3% of the total energy consumption in the United States was supplied by biomass, and it recently surpassed hydroelectric energy as the largest domestic source of renewable energy. Similarly, the European Union received 66.1% of its renewable energy from biomass, which thus surpassed the total combined contribution from hydropower, wind power, geothermal energy, and solar power. In addition to energy, the production of chemicals from biomass is also essential; indeed, the only renewable source of liquid transportation fuels is currently obtained from biomass.

Catalytic Transformation of Lignin for the Production of Chemicals and Fuels

Abstract: and Fuels Changzhi Li,† Xiaochen Zhao,† Aiqin Wang,† George W. Huber,†,‡ and Tao Zhang*,† †State Key Laborotary of Catalysis, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China ‡Department of Chemical and Biological Engineering, University of WisconsinMadison, Madison, Wisconsin 53706, United States

A review of catalytic upgrading of bio-oil to engine fuels

Abstract: As the oil reserves are depleting the need of an alternative fuel source is becoming increasingly apparent. One prospective method for producing fuels in the future is conversion of biomass into bio-oil and then upgrading the bio-oil over a catalyst, this method is the focus of this review article. Bio-oil production can be facilitated through flash pyrolysis, which has been identified as one of the most feasible routes. The bio-oil has a high oxygen content and therefore low stability over time and a low heating value. Upgrading is desirable to remove the oxygen and in this way make it resemble crude oil. Two general routes for bio-oil upgrading have been considered: hydrodeoxygenation (HDO) and zeolite cracking. HDO is a high pressure operation where hydrogen is used to exclude oxygen from the bio-oil, giving a high grade oil product equivalent to crude oil. Catalysts for the reaction are traditional hydrodesulphurization (HDS) catalysts, such as Co–MoS2/Al2O3, or metal catalysts, as for example Pd/C. However, catalyst lifetimes of much more than 200 h have not been achieved with any current catalyst due to carbon deposition. Zeolite cracking is an alternative path, where zeolites, e.g. HZSM-5, are used as catalysts for the deoxygenation reaction. In these systems hydrogen is not a requirement, so operation is performed at atmospheric pressure. However, extensive carbon deposition results in very short catalyst lifetimes. Furthermore a general restriction in the hydrogen content of the bio-oil results in a low H/C ratio of the oil product as no additional hydrogen is supplied. Overall, oil from zeolite cracking is of a low grade, with heating values approximately 25% lower than that of crude oil. Of the two mentioned routes, HDO appears to have the best potential, as zeolite cracking cannot produce fuels of acceptable grade for the current infrastructure. HDO is evaluated as being a path to fuels in a grade and at a price equivalent to present fossil fuels, but several tasks still have to be addressed within this process. Catalyst development, understanding of the carbon forming mechanisms, understanding of the kinetics, elucidation of sulphur as a source of deactivation, evaluation of the requirement for high pressure, and sustainable sources for hydrogen are all areas which have to be elucidated before commercialisation of the process.

Bright Side of Lignin Depolymerization: Toward New Platform Chemicals

Abstract: Lignin, a major component of lignocellulose, is the largest source of aromatic building blocks on the planet and harbors great potential to serve as starting material for the production of biobased products. Despite the initial challenges associated with the robust and irregular structure of lignin, the valorization of this intriguing aromatic biopolymer has come a long way: recently, many creative strategies emerged that deliver defined products via catalytic or biocatalytic depolymerization in good yields. The purpose of this review is to provide insight into these novel approaches and the potential application of such emerging new structures for the synthesis of biobased polymers or pharmacologically active molecules. Existing strategies for functionalization or defunctionalization of lignin-based compounds are also summarized. Following the whole value chain from raw lignocellulose through depolymerization to application whenever possible, specific lignin-based compounds emerge that could be in the fu...