Study On Biomass Char Sulfonic Acids As Highly-efficient Catalysts For Synthesis Of Dioctyl Adipate

Dioctyl adipate(DOA)is a good cold-resistant plasticizer,and has been used more and more widely in plastic processing industry due to its high plasticizing efficiency and low toxicity.Biomass char sulfonic acids(BCSAs),as cheap solid acid catalysts,have advantages of convenient operation and easy separation of the product in synthesis of DOA.This thesis,from the perspective of environmentally-friendly catalysis,researches the preparation of new and highly-efficient BCSAs and their catalytic performances for the esterification of adipic acid to synthesize DOA and have get the following achievements.(1)A series of glucose-based carbon sulfonic acids(GCSAs)were prepared by the sodium silicate-catalyzed hydrothermal carbonization of glucose,followed by its sulfonation with fuming sulphuric acid.The effects of the catalyst sodium silicate and the additive melamine on the acidic density of GCSAs and their catalytic properties have been checked.This method get the advantages of using cheap raw materials and mild carbonization conditions,as well as achieving higher sulfonic groups(2.83 mmol/g)and excellent esterification activity.However,there is also disadvantages as low carbonization yield and poor catalyst stability.The addition of melamine can obviously increase the carbonization yield and improve the stability of catalyst,but result in the decreased sulfonic acid to 1.37mmol/g.(2)A series of bamboo char sulfonic acids(BCSAs)were synthesized via catalysis pyrolysis under moderate to high temperature and then sulfonation with fuming sulphuric acid and the effects of catalyst A and carbonization temperature on the acidic density and catalytic performance of BCSAs have studied.The results show that catalytic pyrolysis,in compared with direct pyrolysis,can not only reduce significantly the formation of tars,obviously improve the carbonization yield(increase nearly 30%)and the sulfonic acid amount(2.19mmol/g),but also the esterification and recovery performances of BCSAs have improved significantly in the catalytic synthesis of DOA.Under the best preparation conditions,the BCSA catalyst was used for nine times,the average esterification and recovery rate are all over 92%.It showed good catalytic activity,but there are also get a short of the fall off sulfonic acid groups.(3)Series of new bamboo char sulfonic acids with ultra-high sulfonic acid groups(HBCSAs)were firstly prepared through the catalysis pyrolysis or hydrothermal carbonization in the oven under low temperature and then sulfonation with fuming or concentrated sulphuric acid and the effects of catalyst A or B and additive C,carbonization temperature and times on the carbonization yield and the sulfonic acidity and catalytic esterification activity of HBCSAs have been researched in details.The results show that the char sulfonic acid catalysts prepared by only using the A or B as a carbonization catalyst under optimized condition show excellent esterification activity and good stability,but their sulfonic sites are not improved obviously compared to the above method carbonized under moderate to high temperature.Interestingly,using the catalyst B-catalyzed hydrothermal carbonization of bamboo in the presence of the additive C can not only significantly improve the carbonized yield,but also prepare the ultra-high sulfonic acid groups of HBCSA catalysts and their sulfonic acid groups(3.27?4.93mmol/g)are far more than the current level reported.More importantly,HBCSA catalysts possess an excellent activity and good reusability,which can be reused for eight times,achieving the average rate of esterification above 99%and the average rate of recovery above 95%.