Preparation Of Rich Ydrocarbon Biofuel From Catalytic Cracking Of High Acid Value Oils With Functionalized KIT-6

Faced with the environmental problems of global warming and the energy crisis of the gradual depletion of fossil fuel reserves,sustainable and environmentally friendly hydrocarbons are urgently needed to replace fossil fuels.As a low pollution alternative energy source,biofuel has high potential,and researchers are increasingly paying attention to producing clean biofuels from bio fats.The production of biofuels from waste cooking oil has the advantages of low cost,abundant sources,and not competing with food sources.However,due to its high viscosity,poor stability,high acid value,and large amounts of impurities,it cannot be directly used as a transportation fuel.To address these issues,several basic mesoporous molecular sieves,acid-base synergistic mesoporous molecular sieves,and acid-base synergistic micro-mesoporous molecular sieves were designed and synthesized in this paper,and used as catalysts for catalytic cracking reaction to prepare biofuel,which effectively improved the yield of liquid biofuel,reduced the acid value of the oil,and obtained rich hydrocarbon biofuel with excellent performance.The specific research contents are as follows:The basic mesoporous molecular sieve Me-KIT-6（Me=K,Ca,Mg,Ba）was prepared by hydrothermal synthesis.The synthesized molecular sieve was characterized by XRD,N₂ adsorption/desorption,TEM,and CO₂-TPD.The results showed that the synthesized molecular sieve had a mesoporous structure,with Mg-KIT-6 having better long-range ordering and crystallinity;Mg-KIT-6 has the largest specific surface area,pore volume,and pore diameter,indicating a more developed pore structure;Mg-KIT-6has the largest amount of weak base,strong base,and total base,with the strongest alkalinity.Under the optimal process conditions of m（catalyst）:m（oil）=1:30,pyrolysis temperature 430℃,and pyrolysis time 120 min,Mg-KIT-6 exhibited even better catalytic performance,with a liquid product yield of 62.7%,including a hydrocarbon content of 75.74%,and a coke yield and acid value of 17.3%and 49.03 mg KOH/g,respectively.The effect of doping amount of Mg element on the catalytic performance of Mg-KIT-6 was investigated.The results showed that Mg-KIT-6 mesoporous molecular sieve with n（Mg）:n（TOES）=1:30 had better catalytic performance.The catalytic stability of the molecular sieve showed that Mg-KIT-6 still exhibited good catalytic performance after being used for 5 times.M-KIT-6（M=Al,Zr,Ni,Zn）was prepared by hydrothermal synthesis,and then Me O/M-KIT-6（Me=K,Ca,Mg,Ba）was prepared by impregnation.The synthesized molecular sieves were characterized by XRD,N₂ adsorption/desorption,TEM,NH₃-TPD,and CO₂-TPD.The results showed that Mg O/Zn-KIT-6 had a better long-range ordered mesoporous structure,a high specific surface area,and a high acid and alkali content.When Mg O/Zn-KIT-6was used as the catalyst for the cracking reaction of waste cooking oil,the results showed that under the optimal process conditions,the liquid yield was as high as 64.3%under the optimal process conditions.The content of hydrocarbon compounds was as high as 79.18%,and the acid value was also reduced to the lowest value of 21.22 mg KOH/g.The effects of doping amount of Zn element and loading amount of Mg metal oxide on catalytic cracking reaction were investigated.The results showed that Mg O/Zn-KIT-6 with n（Zn）:n（TOES）=1:30 and n（Mg）:n（Zn）=2 had the best catalytic effect,the highest liquid yield,the lowest acid value,and the most concentrated product distribution of the obtained biofuel.The catalytic stability of the molecular sieve showed that the Mg O/Zn-KIT-6 active component was unstable,and after being used for 5 times,both acidic and alkaline sites were lost,leading to a decrease in catalytic performance.Micro mesoporous molecular sieve M-Beta-KIT-6（M=Al,Zr,Ni,Zn）was prepared by hydrothermal synthesis method,and then Me O/M-Beta-KIT-6（Me=K,Ca,Mg,Ba）was prepared by impregnation.The micro mesoporous molecular sieve was characterized by XRD,N₂ adsorption/desorption,TEM,NH₃-TPD,and CO₂-TPD.The results showed that Mg O/Zn-Beta-KIT-6 has a regular micro mesoporous structure,high specific surface area,high acid and alkali content.It was used to catalyze the cracking reaction of waste edible oil,and the results showed that under the optimal process conditions,the liquid yield of Mg O/Zn-Beta-KIT-6 was as high as 66.75%,with a hydrocarbon compound content of 85.15%and an acid value of 13.33 mg KOH/g.The effect of different silicon aluminum ratios on catalytic cracking reaction was investigated.The results showed that when the molar ratio of silicon to aluminum was 60,the prepared Mg O/Zn-Beta-KIT-6 had the best catalytic effect,the highest liquid yield,the lowest acid value,and the product distribution of the obtained biofuel was the most concentrated.The investigation results of the catalytic stability of the molecular sieve showed that after being used for 5 times of Mg O/Zn-Beta-KIT-6,the structure of the composite molecular sieve was not damaged,and there was no significant loss of acidic and alkaline active components.The molecular sieve still showed good catalytic performance.