Preparation Of Biomass Carbon-based Solid Acid And Its Applications In Catalytic Hydrolysis Of Cellulose

The efficient use of renewable resources, such as cellulose, is significant to the sustainable development of our society. The Carbon-based solid acid is one of the important catalysts used for catalytic hydrolysis of cellulose. It has several advantages, such as non corrosive, recyclable and easy to separate. But there are still problems such as the acid amount of the carbon-based solid acids obtained up to now is relatively low and their catalytic activity is still not strong enough.In this work, the effect of different preparaton methods, conditions and biomass resoures used on the acid amount and the microstructure was systematically studied. The effect of the acid amount, surface structure and functional groups of the carbon-based solid acid on the performance of catalytic hydrolysis of cellulose has been investigated: The research work carried out can be divided into three parts:(1) The carbon-based solid acid(C-SO3H) was prepared by using p-toluenesulfonic acid and sucrose with one-pot method. The preparation conditions were optimused. With a feed ratio of p-toluenesulfonic acid to sucrose charge at 2:2 and carbonized at 180 oC for 24 h, the acid amountof-SO3 H reached as high as 1.387 mmol·g-1. It was found that catalytic activity was increased with the increase of its acid amount, and the catalyst prepared in this way has very little amount of other functional groups such as –COOH and –OH on the the catalst surface.(2) The porous carbon-based solid acid was prepared from biomass resoures with two step method. The effect of the carbonization temperature, the sulfonation condition and the type of biomass on the acid amount, the surface structure and the catalytic activity of the hydrolysis of cellulose were systematically studied. The results indicated that the acid amount of the carbon-based solid acid obtained depends mainly on the carbonization temperature or essentially the carbonization degree of the biomass. By carbonizing sucrose at 400? for 3h and then sulfonating the carbonized sucrose at 180? for 8h, the resulted solid acid(MC-SO3H)gave a total acid amount of 5.69 mmol·g-1 and a sulfonic acid amount of1.46 mmol·g-1, respectively. Applied in the hydrolysis of microcrystalline cellulose, it can result a total reduced sugar(TRS) yield of 51.0% and a glucose yield of 45.0%, respectively. The biomass sources and the carbonization temperature has a great effect on the microstructure of the carbon-based solid acid. It is found that honeycomb macroporous structure is more favourable for the hydrolysis of cellulose. Besides, the carbon-based solid acid prepared by two-step method has higher –COOH and –OH amount. Compared with the carbon-based solid acid preparedby one-pot method, it is found that the polar group, such as –COOH and–OH, have synergistic catalytic effect on the hydrolysis of cellulose.(3) A solid acid catalyst(MC-Cl-SO3H), containing both –Cl and–SO3H group, has been successfully prepared by chloridizing and sulfonating prous carbon. It was shown that the Carbon-based solid acid with –Cl group has a better catalytic activity, and the –Cl group has apparently a better synergy effect with-SO3 H than the –COOH and –OH group. The anlysis of the kinetics of catalytic hydrolysis of cellulose by using MC-Cl-SO3 H shows that the reaction activation energy is 95.45kJ/mol, which is lower than that of other carbon-based solid acids.