Catalytic Conversion Of Lipid To Fuels And Value-added Chemicals

The effective conversion of biorenewable feedstock rich in fatty acids to valuable fuels and chemicals is highly desirable.This dissertation focuses on the cutting edge approach to design,implementation,and evaluation of the heterogeneous catalysts for the quantitative transformation of natural oils,fatty esters,and fatty acids to fatty alcohols,diesel range alkanes and alpha olefins.Thus,three main chemical processes e.g.,hydrogenation,decarbonylation and dehydration occurred during the formation of fatty alcohols,diesel range alkanes,and?-olefins,respectively.Former two processes are aqueous phase hydrogenation and hydrodeoxygenation?HDO?reactions with high yield of targeted products fatty alcohols and diesel-range hydrocarbons over heterogeneous carbon catalysts at relatively low temperatures.Likewise,water is ubiquitous and environmentally friendly solvent which can easily separates the fatty alcohols and alkanes via biphasic separation.The developed methods are safer,less costly and a one-pot hydrothermal green processes.The designed catalysts exhibit high activity,durability,sustainability and environmental friendliness.To best of our knowledge,fatty alcohol dehydration to?-olefins?92%?over mixed nano sized alumina and thoria catalysts,is the novel contribution compared to data reported in the literature.?1?Ruthenium nanoparticles supported on highly hydrophilic mesoporous carbon catalyzed low-temperature aqueous-phase hydrodeoxygenation of microalgae oil to alkanesThe second chapter is related to the aqueous-phase hydrodeoxygenation of the platform chemical algae oil and stearic acids into alkanes.The processing of an energy carrier such as microalgae oil into valuable fuels and chemicals is quite promising.Aqueous-phase processing is suitable for this purpose,since the separation of intrinsic water from the algae cell is difficult.In this study,we synthesized ruthenium?Ru?nanoparticles supported on highly hydrophilic mesoporous carbon to catalyze the quantitative HDO of microalgae oil to alkanes in a one-pot process at low temperatures?140°C?in the aqueous-phase.The mesoporous carbon was obtained by single-step calcination of starch and zinc chloride in nitrogen.The as-obtained carbon showed high surface area and pore volume,allowing high dispersion of Ru nanoparticles.The surface of the carbon material was rich in hydroxyl groups,as evidenced by X-ray photoelectron spectroscopy?XPS?,infrared?IR?spectroscopy,and thermogravimetric analysis?TGA?measurements.As a result,the carbon material contacted preferably with the water phase versus the organic phase,improving the accessibility of substrates.On the other hand,the contact angle test results speculated the superior hydrophilic nature of mesoporous Ru/C?zinc chloride starch?than commercial Ru/C.Both kinetics modeling and in situ IR monitoring in water revealed the superior performance of the hydrophilic mesoporous Ru/C compared to a commercial Ru/C for the tandem hydrogenation of stearic acid and decarbonylation of stearyl alcohol.The herein designed hydrothermal carbon material was highly active,environmentally benign,sustainable,and recyclable material,and could be potentially used for other hydrogenation reactions in the aqueous phase.?2?Highly selective and low-temperature hydrothermal conversion of natural oils to fatty alcoholsThe conventional methods for the production of fatty alcohols from triglycerides or acids require harsh temperature conditions?200–400°C?,high H₂ pressures?20–30MPa?and non-polar polluting solvents over zinc-or copper-chromite?toxic?catalysts.This third chapter focuses on the quantitative transformation of natural oils,fatty esters,and fatty acids to fatty alcohols over N-modified carbon?N-C?supported RuSn catalysts in water at low temperatures?140–180°C?.Fatty alcohols are the valuable commodity non-ionic surfactants used as food additives,industrial solvents,lubricants,hair conditioners,shampoos,resins,perfumes,bio-fuels,health supplements and pharmaceuticals.This developed aqueous-phase hydrogenation is a one-pot green process,safer and less costly according to the main rules of sustainable chemistry.The catalyst was synthesized via a one-pot carbonization of glucose,melamine and zinc chloride with the incorporation of ruthenium and tin nano particles by wet impregnation method.Importantly,the presence of Sn nanoparticles,pyridinic,and pyrrolic nitrogen in the modified N-C support favoured the good dispersion of Ru nanoparticles,constructed the hydrophilic property of the catalyst for staying in the water layer,and facilitated the adsorption of the carbonyl groups.After strongly interacting with the carbonyl group of fatty acids over Sn nanoparticles and N-groups,Ru nanoparticles catalyzed the further acid hydrogenation to the intermediate aldehyde,and subsequently to the target fatty alcohol in a fast rate.This study provides a useful and simple method for synthesizing of highly hydrothermal-stable metal supported carbon catalyst,which can facily and selectively hydrogenate the aqueous biomass to value-added chemicals.?3?Selective synthesis of?-olefins by dehydration of fatty alcohols over alumina–thoria mixed catalystsThe fourth chapter focuses on the selective and high-yield production of?-olefins by alcohol dehydration,and such process is challenging because the isomerization and polymerization olefin products are more thermodynamically stable.In this contest,we prepared a physical mixture of nano-sized alumina?Al₂O₃ⁿ?and thoria?ThO₂?with high efficiency and selectivity towards the production of?-olefins from stearic alcohol(100%conversion,92%yield of?-olefin,rate:2.9 mmol·g^-1·h^-1,solvent:dodecane,300^oC).To our best knowledge,this is the most efficient system developed for fatty?-olefin production from fatty alcohols,as compared to data reported in literature.Dehydration experiments of cis-and trans-2-methyl cyclohexanol over Al₂O₃ⁿrevealed the reaction to proceed by anti-elimination,which was favored by the abundance of Lewis acidic sites(LAS,0.457 mmol·g^-1)and Lewis basic sites(LBS,0.567 mmol·g^-1)on the porous surface of Al₂O₃ⁿ.LAS adsorbed and eliminated the hydroxyl groups?–OH?of stearic alcohol,generating a carbonium ion?carbocation?intermediate,which was subsequently,converted to the alkene as final products over the LBS.However,the selectivity and yield of?-olefin were comparatively low over pure Al₂O₃ⁿ due to the formation of isomeric olefin products.Interestingly,the addition of ThO₂ increased the yield of?-olefin up to 92%owing to the strong adsorption of this compound on the catalytic surface at high temperatures?300°C?,as evidenced by in situ Fourier transform infrared spectroscopy?FTIR?-ethylene adsorption analyses.Consequently,ThO₂ hindered the undesired isomerization and oligomerization of?-olefin taking place over LAS,thereby enhancing the yield of?-olefin products.