Mesoporous Silica SBA-16 Surface Modification Of Adjacent Proton Acids To Research The Synergistic Catalytic Effect

Enzyme as a bio-catalyst,which compares with inorganic catalyst has many advantages,such as high catalytic efficiency(If they can be compared,the catalytic efficiency of the enzyme can generally be 1010 times to inorganic catalyst),high degree of specificity and high purity of the product[1].In addition,a lot of enzyme has two catalytic centers,the two catalytic centers interact with each other,resulting in high efficient catalysis[2].Inspired by the enzyme,we simulated enzyme in its structure and action from the concept to develop new synthetic catalyst,which has excellent prospects[3].Given this idea is complicated,in this paper we started from simple model of catalysts mainly researched adjacent proton acid synergistic catalytic effect and finally achieved a clear results.Firstly,we accurately prepared the mesoporous molecular SB A-16 with the uniform pore size and the large surface area,then modified the SBA-16 with sulfur-containing silane coupling agent named bis-(3-triethoxy silyl propyl])-tetrasulfide,then with oxidation treatment,removed the middle two sulfur of the sulfide,finally we got the two close sulfonic acid,"two acid centers" catalyst(hereinafter called "the pair"acid catalyst).On the other hand,we also modified the SBA-16 surface with(3-mercaptopropyl)triethoxy silane and oxidized it,got the distant,randomly distributed single acid catalyst(below,also named as "single acid" catalyst).The acid sits are far away from each other and have no reaction.We had done some necessary characterizations of the two catalysts to get their physical chemical properties and used the ethanediamine adsorption experiment to verify the propinquity of the acid.The results were consistent with the model of the two catalysts we had supposed.We controlled the acidity of the two kinds of catalysts("the pair" acid catalyst and the "single acid" catalyst)the same,then compared their performances in catalyzing dehydration of fructose,calculated the reaction speed and activation energy.Finally,we verified that when the two acid sit were nearby,the catalytic reaction would has faster speed and the activation energy were much lower.This result provided valuable new ideas for the design of high performance catalyst.