Preparation Of Macroporous Bulk Vegetable Oil Hydrodeoxygenation Catalyst

Current Society,the shortage of fossil energy resources and the increasing demand for energy resources in social development have led to the development of environmentally friendly second-generation biodiesel receives more attention in worldwide.At present,common catalysts for hydrodeoxygenation of vegetable oils have problems such as low activity and poor hydrothermal/ mechanical strength stability.Therefore,the development of catalysts with high activity and high hydrothermal/ mechanical strength stability is the key issue to the development of biodiesel technology.In this paper,a bulk hydrodeoxygenation catalyst was prepared by sol-gel method.The hydrodeoxygenation activity of the catalyst was evaluated in a micro fixed bed reactor.The effects of pore-enlarging agent addition,binder on catalyst activity and hydrothermal/mechanical strength stability are mainly investigated,and the corresponding catalysts were characterized by detailed instrument characterization,to understand the relationship between performance and properties of the catalyst.The studying results of the effect of the pore-enlarging agent on the performance of the catalyst indicate that for the preparation of bulk hydrodeoxygenation catalyst prepared using sol-gel method,acetylene black is the most suitable pore-expanding agent,and the suitable amount of acetylene black is 25g/(Mo+Ni)mol.The addition of acetylene black has no significantly affect on the crystal form and crystallization degree of the catalyst,but effectively increases the specific surface area,pore size and acid amount of the catalyst,thereby effectively improving the hydrodeoxygenation activity of the catalyst.The studying results of the influence of binder on the performance of the catalyst indicate that the use of a suitable binder for preparing the catalyst not only maintains the catalyst with high reactive activity,but also effectively improves the hydrothermal/mechanical strength stability of the catalyst,and the catalyst using aluminum hydroxide dry gel/diatomite with mass ratio of 2:1 as binder exhibited high activity and hydrothermal/mechanical strength stability.Using the diatomaceous earth instead of the part aluminum hydroxide dry glue as a binder could effectively increase surface area,pore diameter and acid amount of the catalyst,and also effectively improve hydrothermal/ mechanical strength stability of the catalyst.The results of scale-up preparation of catalysts show that the catalyst exhibits excellent catalytic activity and stability at the conditions of hydrogen oil volume ratio 200,2MPa pressure,space velocity 2h-1,reaction temperature 330°C,310°C and a reaction time 250 h.The catalyst prepared by scale-up has a relatively stable hydrodeoxygenation activity within 250 h,but the activity of the catalyst is slightly lower than that of the catalyst prepared in the laboratory.The results of the reaction conditions on the reaction pathway of Jatropha oil over the catalyst show that the hydrodeoxygenation reaction path of Jatropha oil over the catalyst gradually increases shift from reduce the number of carbon chains by one(decarboxylation,decarbonylation)to direct the number of carbon chains remains the same(water removal)with the increase of space velocity?the decrease of reaction temperature and the extension of the reaction time.