Preparation, Characterization, And Application Of Biomass Carbon-Based Solid Acid And Alkali Catalysts

Biomass is biological material formed by a class of green plants in photosynthesis which has cellulose, hemicelluloses and lignin, and then subsequently lost after the evolution of physiological and metabolic functions.The biomass could be renewable, widely distributed, a variety of forms, using diverse ways and is good environment-friendly material. At present, biomass can be used to prepare the activated carbon, biofuels (solid, liquid, gas), ethanol and other chemical research For the further use of the biomass resources, the biomass materials are carbonized to biomass carbon-based materials (CBMs) whose can be chemical modification. Here, we prepared novel biomass carbon-based acid and alkali materials using corn straw as materials. The main researches were as follows:1. In this Paper, corn straw as raw material to prepare CBMs via N2 protection. The carbon-based sulfonic acid (CBSA) was prepared via sulfonating the CBMs by oleum. The amount of acid of CBSA was 2.6 mmol·g-1 under the optimized conditions. The catalyst was characterized by the following analysis means, including FTTR, XRD, Raman, XPS, TG, EA, etc. The FTIR spectra showed that sulfonic acid groups were successfully connected to the CBMs; the XRD analysis demonstrated that conjugated aromatic structure formed in the CBMs surface; the Raman spectra showed that a single graphite surface or conjugated aromatic structure existed in the CBMs; the TG characterization showed that sulfonic acid groups started to fall off at 523 K, evidencing that sulfonic acid groups had good thermal stability; surface acid analysis showed that the largest acid amount in the catalyst was 2.6 mmol/g.2. This work focuses on the catalytic performance of CBSA in esterification, self-condensation of cyclohexanone. In the esterification which catalyzed by CBSA, a quantitative yield (98%) of ester was achieved, using the most active sulfonated catalyst at 333 K with a 7 wt% catalyst/oleic acid ratio for 4 h, at a 7:1 molar ratio of methanol/oleic acid, the selectivity of ester came up to 100%. CBSA had a perfect catalytic activity in self-condensation of cyclohexanone which the conversion of cyclohexanone was 98.2%, and CBSA had good circulation usability.3. Corn straw as raw material to prepare CBMs via N2 protection. Use the Ce4+ as an initiator to trigger a graft copolymer with diethylenetriamine through free radical copolymerization. This was an alkaline modification of CBMs. The catalyst was characterized by FTIR, XRD, Raman, XPS etc. The FTIR spectra showed that only carbonized temperature at 673 K or 723 K and carbonized time for 1 h of CBMs can be successfully grafted amino by radical polymerization; the XRD analysis demonstrated that conjugated aromatic structure formed in the CBMs surface; the Raman spectra showed that a single graphite surface or conjugated aromatic structure existed in the CBMs. Meanwhile, in order to investigate the preparation of the carbon-based solid alkali catalytic performance, we used Knoevenagel condensation and transesterification as probe reaction. Using the most active alkali catalyst at 353 K with a 0.1 g catalyst for 1 h, at a 1:1 molar ratio of reactant, a quantitative yield (25.7%) was achieved. Because of the alkalescence of alkali catalyst, it had no catalytic activity for transesterification.We conclude that these novel preparation methods can pave new ways for the preparation of CBMS, and for preparation of biomass carbon-based acid and alkali multifunction materials, since much more materials can be obtained by the current methods.