Preparation Of Coal-based Solid Acid Catalyst And Its Catalytic Esterification Performance

Acid catalysts play an indispensable role in industrial production.In order to avoid the disadvantages of traditional homogeneous acid catalyst,such as corrosion of equipment,large amount of waste water,difficult separation from the product and environmental pollution,heterogeneous catalyst became popular.In recent years,carbon-based solid acid catalysts have attracted extensive attention due to their low cost,no pollution and wide source of raw materials.This experiment using the resource advantage of Inner Mongolia region,in order to guide the victory of lignite coal mine as raw material,through step carbonization sulfonated,pyrolysis carbonization sulfonated and change the different pyrolysis atmosphere preparation coal base solid acid catalyst,and used for preparation of oleic acid and methanol catalyzed esterification of biodiesel,with biodiesel esterification rate as the index,to evaluate the activity of catalyst,The catalysts were analyzed and characterized by IR,EA,BET,SEM,XRD and TG-DTG.1.Coal-based solid acid catalyst was prepared by one-step carbonization sulfonation with concentrated sulfuric acid.The effects of solid-liquid ratio,reaction temperature,reaction time and other factors on the catalytic activity were investigated.A series of methods were used to analyze and characterize shengli lignite and solid acid catalysts.The best reaction conditions were as follows: solid-liquid ratio 1:17.71,reaction temperature111.77℃,reaction time 90 min.The esterification rate of oleic acid and methanol reached95.71%.Three factors effect on the esterification rate of size: solid-liquid ratio > reaction temperature > reaction time,catalyst for a low degree of graphitization of amorphous carbon structure,has the rich oxygen containing functional groups,its surface in dense hole structure,and mainly mesoporous,mesoporous structure of catalyst on the esterification effects play a crucial role.The esterification rate was 57.21% after repeated use for 5 times.2.Solid acid catalyst was prepared by pyrolysis carbonization sulfonation method.Through orthogonal experiment,the optimum preparation conditions were as follows:carbonization temperature: 400℃,carbonization time: 30 min,sulfonation temperature:90℃,sulfonation time: 60 min,and the esterification rate reached 94.95%.The carbonization temperature is the main factor affecting the catalytic activity of the catalyst.Through a series of methods for characterizing the catalytic effect is the best and the worst of the catalyst,the results showed that compared with the worst catalyst,efficient catalyst has a large specific surface area,pore developed,large specific surface and pore structure can be developed as catalyst to provide more active site,it has high catalytic activity.The two catalysts have amorphous carbon structure and have good thermal stability at 100℃.3.Carbon-based support was prepared by changing the pyrolysis atmosphere,and then it was sulfonated to prepare solid acid catalyst.The results showed that the best esterification rates of O-N,C-N and H-N catalysts were 95.29%,96.61% and 96.77%,respectively.The o-N and H-N prepared under different conditions have good catalytic effect on the whole,and the catalytic activity of C-N decreases rapidly when the carbonization temperature reaches 500℃,which is believed to be caused by the compact structure of the carbon-based carrier and the reduction of active sites due to the high carbonization temperature.The results showed that the three catalysts had large specific surface area and well-developed pore structure,and the S element was evenly distributed on the surface and in the pore channel.Compared with O-N and H-N,the specific surface area,pore volume and aperture of C-N are smaller and the degree of non-orientation is larger.The three catalysts have amorphous carbon structure and have good thermal stability at 0-120℃.Compared with pure nitrogen protective gas,the catalyst pore structure prepared by pyrolysis in mixed atmosphere is developed,the specific surface area is larger,and the catalytic effect is better.