Study On The Catalytic Cracking Of Oils For The Production Of Liquid Biofuels By Using Metal Oxide Modified SBA-15 Catalyst

The energy and environmental problems were increasingly severe,liquid biofuels have attracted widespread attention as a clean renewable energy source.In recent years,it is generally believed that biofuels produced by catalytic cracking of cheap oils is a promising process.However,the existing catalysts generally have some shortcomings,such as low biofuel yield,producing many by-products and non-recycling.Therefore,the catalytic cracking reaction of biological oils was studied using cheap oils and mesoporous molecular sieve?SBA-15?modified with basic metal oxide,single metal oxide and composite metal oxide as raw materials and catalysts,respectively.The K₂O/MeO-SBA-15?Me=Ca,Mg,Ba?were used as catalyst to study the catalytic cracking reaction of rubber seed oil.The synthesized catalysts were characterized by X-ray powder diffraction?XRD?,N₂ adsorption-desorption,transmission electron microscopy?TEM?and CO₂ temperature-programmed adsorption-desorption?CO₂-TPD?.The results showed that the synthesized K₂O/MeO-SBA-15?Me=Ca,Mg,Ba?mesoporous materials have long-range ordered mesoporous structure;Alkali strength was enhanced and the number of basic sites were increased after impregnating the potassium nitrate.By studying the effect of potassium nitrate impregnating concentration and reaction conditions on the catalytic cracking of rubber seed oil,the optimal reaction conditions were obtained:the potassium nitrate impregnating concentration was 15 wt%,the reaction temperature was 450 ^oC,the reaction time was 80 min,and the mass ratio of catalyst to rubber seed oil was 1:30.Under the above reaction conditions,the conversion of rubber seed oil and the yield of biofuel were 93.2%and 78.3%,respectively.Finally,the recycling performance of K₂O/MgO-SBA-15 catalyst was studied,and the catalyst after the reaction was analyzed by XRD and FT-IR characteristic techniques.The results showed that K₂O/MgO-SBA-15 has good thermal stability.After reused five times,the structure of K₂O/MgO-SBA-15 catalyst remained intact and the deactivation rate of the catalyst was within a reasonable error range?the biofuel yield was reduced by 6%after reused five times?.MeO-SBA-15?MeO=ZnO,La₂O₃,CeO₂,NiO,MgO?were used as catalysts to study the catalytic cracking reaction of waste cooking oils.The results showed that the synthesized MeO-SBA-15?MeO=ZnO,La₂O₃,CeO₂,NiO,MgO?catalysts had long-range ordered mesoporous structure and good thermal stability;The ZnO-SBA-15catalyst contained more acidic sites,while the NiO-SBA-15 and MgO-SBA-15contained less acidic sites.The effect of catalyst on the catalytic cracking of waste cooking oils was investigated under the reaction conditions,which the reaction temperature was 460 ^oC,the reaction time was 120 min,and the mass ratio of catalyst to waste cooking oil was 1:30.The catalytic pyrolysis results showed that the ZnO-SBA-15 catalyst obtained higher liquid biofuel yield?37.3%?and lower heavy oil yield?39.9%?,while the liquid biofuel obtained using MgO-SBA-15 catalyst had a lower acid value.The ZnO/MgO-SBA-15?Zn wt%=5,10,15,20?were used as catalyst to study the catalytic cracking reaction of waste cooking oils.The results showed that the synthesized ZnO/MgO-SBA-15 mesoporous materials had long-range ordered mesoporous structure;Acid strength was enhanced and the number of acidic sites were increased after impregnating the Zinc acetate.When the zinc acetate impregnating concentration exceeded 10 wt%,the large angle XRD patterns showed that zinc oxide crystal particles were formed on the surface of the molecular sieve.Therefore,the optimum impregnating concentration of zinc acetate was 10 wt%.The optimal reaction conditions were obtained:the reaction temperature was 460 ^o C,the reaction time was100 min and the mass ratio of catalyst to waste cooking oil was 1:30.Under the above reaction conditions,the conversion of waste cooking oil and the biofuel yield were93.0%and 71.5%,respectively.Finally,the catalyst after the reaction were analyzed by XRD and N₂ adsorption-desorption characteristic technologies.The results showed that ZnO/MgO-SBA-15 had good thermal stability.After reused three times,the biofuel yield was reduced by 9%and the ZnO/MgO-SBA-15 catalyst still maintained long-range ordered mesoporous structure.In the catalytic cracking reaction of rubber seed oil and waste cooking oils,the modified-SBA-15 using different types of metal oxides not only overcome disadvantages of the traditional catalyst,but also realize the integrative process of the reaction and separation.This study expands the application of SBA-15 mesoporous molecular sieves in the preparation of biofuels and provides guidance for mesoporous molecular sieves in the catalytic cracking oils into biofuels reaction.