efinery approach of bio-oils derived from fast yrolysis of lignin to jet fuel range hydrocarbons : eaction network development for catalytic onversion of cyclohexanone

This study demonstrated that the bio-oil derived from fast pyrolysis of lignin was excellent candidate to be converted into the jet and diesel fuel range hydrocarbons by catalytic upgrading process. This research addresses specifically the kinetic and mechanism of cyclohexanone conversion using sulfided CoMo/ -Al2O3 catalyst in a fixed-bed flow reactor. The main routes of cyclohexanone upgrading included hydrodeoxygenations (HDO), dehydrogenation, hydrogenation and coupling. The selectivity-conversion analyses at different operating condition indicate that benzene, cyclohexene, phenol, and 2-cyclohexen-1-one formed as primary products and the other main products, 2-methylphenol, cyclohexylbenzene, biphenyl, 2-phenylphenol, 2-cyclohexylcyclohexan1-one, 2-cyclohexylidenecyclohexane-1-one and 2-cyclohexylphenol appeared as non-primary products. An approximate reaction network and a first order kinetic model are developed to determine kinetic parameters. Kinetic investigations indicate that among the various reactions on sulfided CoMo/Al2O3, HDO is characterized by the highest rate and that selectivities for oxygen removal are favored by operation at higher temperatures and pressures. The apparent activation energy for the HDO reaction that leads to benzene formation is approximately 35.6 kJ/mol; coupling is the reaction class characterized by the highest apparent activation energy. The pseudo-first-order rate constants for formation of the main products of cyclohexanone conversion decrease in the following order: benzene >2-cyclohexylidenecyclohexane-1-one > cyclohexylbenzene > 2-cyclohexen1-one > 2-phenylphenol > phenol > cyclohexene > 2-cyclohexylphenol > 2-methylphenol > 2cyclohexylcyclohexan-1-one > biphenyl. © 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. (Bezergianni et al., 2009; Mohan et al., 2006; Saidi et al., 2014b). In . Introduction n recent years, due to increasing demand for diesel and jet fuel and rowing awareness of important environmental issues, there is an mmense interest in developing new generation hydrocarbon biofuels, ith a particular focus on green aviation biofuels (Alonso et al., 2010; zernik and Bridgwater, 2004; Hosseinzadeh et al., 2015; Naik et al., 014; Rahimpour et al., 2016; Saidi et al., 2016, 2014b; Shemfe et al., 2016; ∗ Corresponding author. E-mail addresses: m.saidi@eng.sku.ac.ir, majidsaidi65@gmail.com ( ttp://dx.doi.org/10.1016/j.cherd.2017.03.029 263-8762/© 2017 Institution of Chemical Engineers. Published by Elsev Wang et al., 2015). Depend on the type of feedstock, several promising technology such as gasification, Fischer–Tropsch synthesis (FTS), hydro-processing technologies, including hydro-treating, deoxygenation, isomerization/hydrocracking and catalytic hydro-thermolysis that convert biomass-based materials into jet fuel substitutes are available at commercial scale or research and development stage M. Saidi). FTS technology as a developed and commercialized route to transform ier B.V. All rights reserved. 394 chemical engineering research and design 1 2 1 ( 2 0 1 7 ) 393–406 lignocellulose biomass into jet fuel hydrocarbons range (particularly alkanes), bio-syngas produces via biomass gasification and subsequently cleaning and conditioning of crude syngas will be performed (Liu et al., 2013; Yan et al., 2013). High pressure FT synthesis and upgrading of crude fuels for jet fuel applications is the final step. Based on international standards for certifying aviation fuel such as American Society for Testing and Materials (ASTM D1655), the most important specifications required to reach bio-jet-fuels are acceptable viscosity, heating value, electrical conductivity, freeze point temperature, flash point, aromatics content, acidity and mercaptan concentration. Typically the jet fuels are comprised of paraffins, naphthenes and aromatics (Branca et al., 2003; Czernik and Bridgwater, 2004; Oasmaa and Czernik, 1999). Nonetheless, in the well-developed hydrotreating technologies such as FTS, it is hard to attain acceptable compositions of cyclic paraffins and aromatics jet fuels. Lignin as a main underutilized constituent of lignocellulosic biomass is highly aromatic, with a polymeric structure characterized by ether linkages and hydroxy and methoxy groups and it has been proven to potentially produce biofuels with aromatic structure by various strategies (Saidi et al., 2015a,b; Zakzeski et al., 2010). Fast pyrolysis of biomass, a process that is relatively well developed, is one of the viable processes to convert lignocellulosic biomass to bio-oils (Akhtar and Amin, 2011; Wang et al., 2012). In fast pyrolysis, lignin is heated in the absence of air to temperatures between about 650 and 800 K and it will be converted substantially into compounds such as phenol, anisole, guaiacol, cresol, syringol, etc. Products of the conversion of these compounds with H2 include cyclohexanone, and only little research has been done to investigate the catalytic reactions of this compound with H2 (Nimmanwudipong et al., 2011a; Runnebaum et al., 2012). The lignin-derived bio-oils are unable for use directly as a fuel because of detrimental properties compared to petroleum fuels, such as much lower energy density, poor thermal and chemical stabilities, high viscosity and oxygen content. To meet the requirements of the conventional transportation fuels, lignin-derived bio-oils have to be upgraded to eliminate total or partial oxygenates and unsaturated degree prior to its practical application as valuable fuel (Alonso et al., 2010; Nimmanwudipong et al., 2011b; Runnebaum et al., 2011). Among the upgrading approaches for jet fuels, hydrodeoxygenation (HDO) is introduced as a promising process to remove the oxygen content under high temperature and pressure of hydrogen in the presence of a cata-