CuO/SiO_2催化剂上甘油脱水制α-羟基丙酮

在固定床反应器中,以甘油脱水制备α-羟基丙酮反应为研究对象,考察了CuO/SiO_2催化剂的制备条件以及反应条件对催化剂性能的影响。实验结果表明,催化剂的最佳制备条件为:CuO负载量(质量分数)为20%,在450℃下焙烧4h;采用该条件下制备的催化剂,在进料重时空速为1.4h~(-1)、反应温度为300℃、甘油溶液的质量分数为20%、反应时间6h的条件下,甘油的转化率达到99.28%,α-羟基丙酮的选择性为58.03%。通过XRD,NH_3-TPD,TG-DTA等手段对CuO/SiO_2催化剂进行了表征,表征结果显示,最佳制备条件下制得的CuO/SiO_2催化剂具有最优的表面酸性分布和最合适的表面微结构,从而在甘油脱水反应中表现出最佳的催化性能。     

大肠杆菌Lin43利用甘油产丙酮醇-通过敲除gloB基因改善丙酮醛耐受性

采用重组大肠杆菌Lin 43利用甘油产丙酮醇。为了改善菌株对丙酮醛的耐受性,采取敲除glo B基因而不是gloA基因以阻断丙酮醛的脱毒途径。实验结果表明,菌株Lin43ΔgloB对丙酮醛的耐受性要明显优于Lin43ΔgloA。在含20 g·L-1的甘油磷酸盐缓冲液中,通过26 h静息细胞转化,菌株Lin43·gloB pCA24N-yqhE丙酮醇产量达到2.30 g·L-1,并能耐受3.5 mmol·L-1的丙酮醛。同时Lin43·gloB pCA24N-yqhE实现重复发酵,第二轮发酵的产量可达1.53 g·L-1,丙酮醇的得率与第一轮相同。     

三组分铜铬催化剂催化甘油制备羟基丙酮的研究

用共沉淀法制备了Cu-Cr-Zn催化剂,考察了Cu/Cr/Zn比、沉淀温度、沉淀时pH值、煅烧温度等制备条件对甘油制备羟基丙酮的影响,并对催化剂进行了表征。结果表明:共沉淀法制备Cu-Cr-Zn催化剂具有较高的催化活性,而且其稳定性和再生能力较好,适宜催化剂制备条件为:Cu/Cr/Zn比为1∶1∶0.5,沉淀温度为70℃,沉淀时pH值为8.0,煅烧温度为400℃,羟基丙酮的选择性可达到90.2%。     

Properties of enzymes which reduce dihydroxyacetone and related compounds in hansenula polymorpha CBS 4732

Hansenula polymorpha CBS 4732 grown on a variety of substrates contained very high activities of enzymes catalyzing the NADH-linked reduction of dihydroxyacetone, acetoin, diacetyl, acetol, methylglyoxal and acetone. The enzymes catalyzing these reductions have been purified and their kinetic properties are described. Three different enzymes were found responsible for the above-mentioned activities, namely: (1) dihydroxyacetone reductase; (2) acetone reductase; and (3) alcohol dehydrogenase. So far, the physiological function of dihydroxyacetone reductase and acetone reductase is obscure. The kinetic properties of dihydroxyacetone reductase and the regulation of the synthesis of this enzyme suggest that it does not function as a glycerol dehydrogenase.     

锌修饰亚铬酸铜催化甘油制备羟基丙酮

以锌修饰的亚铬酸铜为催化剂,考察了锌含量、催化剂煅烧温度、催化剂用量、反应温度等条件对甘油脱水制备羟基丙酮的影响。结果表明:助剂锌修饰作用提高了亚铬酸铜的催化剂活性,延长了催化剂的使用次数,提高了羟基丙酮选择性和产率。适宜催化剂制备及反应条件为:硝酸锌浸渍液浓度为10%,焙烧温度为350℃,催化剂用量为4%,反应温度为220℃,羟基丙酮选择性达88.9%。     

羟基丙酮转化为4-甲基咪唑的研究

以羟基丙酮、甲酰胺、液氨为原料合成4-甲基咪唑。结果表明,在羟基丙酮∶甲酰胺=1∶5,温度160℃,压力1.8~2 MPa,反应5 h条件下,4-甲基咪唑选择性达81.6%。     

生物质甘油催化转化为羟基丙酮

探索了生物质甘油在铜铬催化剂作用下催化转化为羟基丙酮的反应条件,采用乙醇为溶剂,考察了甘油浓度、催化剂用量和反应温度等因素的影响。较优反应条件:反应温度240℃,采用连续滴样的进样方式,甘油浓度80%,未还原的铜铬催化剂[n(Cu)∶n(Cr)=1]用量为原料质量的2.5%,甘油转化率和羟基丙酮选择性分别达到95.4%和89.9%。     

Continuous production of 1,2‐propanediol by the selective hydrogenolysis of solvent‐free glycerol under mild conditions

BACKGROUND: The conversion of glycerol to value‐added derivatives is now critical, owing to the large surplus of glycerol from biodiesel production. The main objective of this work is to develop a novel process for converting solvent‐free glycerol to 1,2‐propanediol. RESULTS: Several catalysts were screened for aqueous‐phase hydrogenolysis of glycerol in an autoclave. The most effective catalysts (Ni/Al₂O₃, Cu/ZnO/Al₂O₃) were further tested for vapor phase hydrogenolysis in a fixed‐bed. Ni/Al₂O₃ did not prove as effective for the production of 1,2‐propanediol because of the high selectivity to CH₄ and CO. Over Cu/ZnO/Al₂O₃, glycerol was mainly converted to the desired 1,2‐propanediol and the reaction intermediate acetol. The production of 1,2‐propanediol was favoured at higher hydrogen pressure. At 190 °C and 0.64 MPa, near complete conversion of glycerol was achieved with 1,2‐propanediol selectivity up to 92%. In addition, a higher concentration (between 43.4% and 0.8%) of acetol was detected and an approximately stoichiometric relationship was found between acetol and 1,2‐propanediol. CONCLUSION: 1,2‐propanediol can be produced with high yields via the vapor phase hydrogenolysis of glycerol over Cu/ZnO/Al₂O₃. Furthermore, the mechanism of 1,2‐propanediol formation is suggested to proceed mainly through an acetol route over Cu/ZnO/Al₂O₃. Copyright © 2008 Society of Chemical Industry