| With the rapid development of economy and undue consumption of oil resources, the utilization of reclyable biomass to produce chemical commodities has become a hot research topic. It is well-known that carbohydrates are widely distributed in nature and glycerol acts as abandunt byproduct of biodiesel. It is reasonable to make use of these resources to produce chemicals. The investigation here was focused on the synthesis of isosorbide diacetate from glucose and preparation of higher alcohol acetate (such as propylene diacetate PGDA, n-propyl acetate PA, ethyl acetate EA) indirectly from glycerol over rutheniumcatalysts.The research began with the preparation of isosorbide diacetate from carbohydrates through hydrogenation and dehydration processes in acetic acid. The catalytic activity of different transition metal choloride (RhCl3, PdCl2 RuCl3) was investigated. It was found that RuCl3/Ph3P composed of active component RuCl3 and ligand Ph3P demonstrates the highest catalytic activity. After that we conducted many experiments to examine the influences of carbohydrates, reaction time, reaction temperature and the hydrogen pressure. Nearly 41.4% yield of isosorbide diacetate from glucose was obtained with 1.6% RuCl3/Ph3P (weight ratio of catalyst to the carbohydrate) under the condition of 220℃,3 MPa and 24 h. It was also found that triacetin was produced under higher pressure. Besides, the feasibility of synthesizing isosorbide diacetate from cellulosic solid waste (waste paper and rice husk) through the same process was also investigated.Then the experiments was focused on the preparation of higher alcohol acetate from glycerol through esterification and hydrogenolysis. Firstly, mixed glycerides of different degree of esterification was synthesized. Then the catalytic activity of RuCl3/PPh3 and carbon nanotube-supported metal Ru nanoparticle catalysts (Ru/MWNT, Ru-MoOx/MWNT, Ru-WOx/MWNT) was studied in the hydrogenolysis of triacetin (TA). The effect of quantity of catalyst, reaction time, temperature and hydrogen pressure was examined. It showed that a good selectivity of PGDA was obtained with RuCl3/PPh3 as main catalyst and KI as promoter. Besides, the selectivity of 1,3-PGDA was better than that of 1,2-PGDA. Under the reaction condition of 4 MPa,220℃,6 h over RuCl3/PPh3, the conversion of TA was 66.8% and a yield of 35.3%,8.7%,9.3% was obtained for PGDA, PA and EA. For Ru/MWNT, the conversion rate of TA was 42.9% and a yield of 6.2%,6.8% and 6.3% was obtained for PGDA, PA and EA for each under the reaction condition of 3 MPa,220℃,24 h. The hydrogenolysis of mixed glyceride was investigated with RuCl3/PPh3 as main catalyst and KI as promoter. The results showed that the yield of higher alcohol acetate increased following the increase of degree of esterification and a maximum yield of 31.6% was achieved for PGDA with the mixed glyceride containing 45.7% (wt%) TA. The preliminary study also focused on the effect of solvent and catalysts on the direct hydrogenolysis of glycerol over Ru catalysts. TEM and XRD were performed to characterize catalysts Ru/MWNT, Ru-MoOx/MWNT, Ru-WOx/MWNT, which showed that nanoparticle catalysts were highly dispersed.Finally, different carbon nanotube-supported Ru-based catalysts for direct conversion of glycerol to higher alcohol was investigated. Several solvents were also studied. The results showed that a selectivity of 53.3% for 1,2-PG was obtained over RuCl3/PPh3 with EA as solvent.The selectivity of 1,2-PG was higher than that of 1,3-PG via Ru-based catalysts. Besides, supported Ru catalyst modified by Fe demonstrated a good catalytic performance with a selectivity of 73.8% for 1,2-PG and a conversion of 43.7% for the glycerol. |
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