Conversion of Biomass into Levulinate Esters as Novel Energy Chemicals

生物质是唯一可替代化石资源获取液态燃料和化学品的可再生资源,近年来由生物质转化合成乙酰丙酸酯引起了研究者们越来越广泛的关注。乙酰丙酸酯是一类重要的化学中间体和新能源化学品,具有高的反应特性和广泛的工业应用价值。目前开发的从生物质资源出发转化合成乙酰丙酸酯的潜在合成途径可概括为4种:直接酸催化醇解法、经乙酰丙酸酯化、经5-氯甲基糠醛醇解和经糠醇醇解。本文分别介绍了这4种转化合成途径的化学反应过程及最新研究进展,从反应合成工艺、催化体系、经济可行性等方面评述了各自的特点与发展趋势,并分析了目前工业规模转化生物质合成乙酰丙酸酯仍面临的一些科学难点。最后,对今后该领域的研究前景进行了展望。Biomass is the only renewable resources on the earth that can derive liquid fuel and fine chemicals to replace the petroleum-based chemicals.In recent years,the development of bioenergy concerning the synthesis of levulinate esters from biomass via chemical/catalytic process has attracted more and more concerns,and extensive research is being carried out worldwide.Levulinate esters,like methyl levulinate,ethyl levulinate,and butyl levulinate,are a kind of important intermediates and energy chemicals having high reactivity and widespread application in many fields.Up to now,there are four developed potential pathways for the synthesis of levulinate esters from biomass conversion,including the direct acid-catalyzed alcoholysis of biomass,the esterification of levulinic acid that from hydrolysis of biomass,the alcoholysis of 5-(chloromethyl)furfural derived from biomass,and the alcoholysis of furfuryl alcohol that from hydrogenation of furfural.In this review,the chemical reaction process and recent research progress for the above four pathways are introduced.The characteristic and development tendency of these pathways are reviewed from the production process,catalytic system and economic feasibility.Based on the present research situation,the technology and engineering barriers for the conversion of biomass to levulinate esters in commercial scales are analyzed and discussed,and the future research trend in the field is prospected.国家重点基础研究发展计划(973)项目(No.2010CB732201);国家自然科学基金项目(No.50776035);中央高校基本业务费专项资金项目(No.2010121077)资

Conversion of Glucose into Butyl Levulinate over Solid Acid SO_4~(2-)/SnO_2 Catalyst

以沉淀-浸渍法合成的SO24-/SnO2固体酸为催化剂,于丁醇体系中催化葡萄糖转化合成乙酰丙酸丁酯。考察了不同反应条件以及催化剂的重复利用性对产物得率的影响,并利用Xrd和nH3-TPd对使用前后的催化剂的结构和酸性进行了表征。实验结果表明:当催化剂于500℃焙烧3 H,用量2.5%,反应温度200℃的条件下反应2 H时,乙酰丙酸丁酯的得率最高达33.1%(摩尔得率,下同);回收利用的催化剂经过焙烧后使用催化性能有所下降,由最初的33.1%下降至回用5次后的12.8%。Xrd和nH3-TPd分析结果表明,使用后催化剂的晶型结构仍保留,但酸强度和总酸量随重复使用次数增加却逐渐降低。Solid acid catalysts SO42-/SnO2 were prepared by precipitation and impregnation method for conversion of glucose to butyl levulinate in butanol.The effects of different reaction conditions and catalyst reuse on yields of butyl levulinate were also investigated.The surface structure and acidity of the fresh and reused catalysts were characterized by XRD and NH3-TPD.The results indicated that butyl levulinate yield of 33.1% could be obtained under the conditions of the catalyst calcined at 500 ℃ for 3 h,catalyst dosage 2.5 %,reaction temperature 200 ℃ and reaction time 2 h.And the catalytic performance for the reused catalysts after calcinations decreased from 33.1% to 12.8% after the fifth reuse.XRD and NH3-TPD results showed that crystallization structure of catalyst was preserved well after reuse,but the acid strength and total amounts of acid were decreased slightly with the increase of the number of reuse.国家973计划资助(2010CB732201); 国家自然科学基金资助项目(U0733001;50776035

Catalytic conversion of glucose to levulinic acid by solid heteropolyacid salts

制备了一系列金属离子修饰的磷钨酸盐(MXH3-2 XPW12O40,M=zn,Cu,CS,Ag)催化剂,并将磷钨酸银盐(Ag3PW12O40)用于水解葡萄糖制备乙酰丙酸的实验中。采用fTIr、Xrd、SEM和EPMA等技术对磷钨酸盐性能进行了表征,并分析了磷钨酸银盐催化剂在反应前后结构和表面元素相对含量的变化。考察了反应温度、反应时间、催化剂用量和葡萄糖浓度等对乙酰丙酸得率的影响。结果表明:合成的磷钨酸盐具有磷钨酸的kEggIn结构,并且Ag3PW12O40催化剂在多次使用后kEggIn结构没有被破坏。在催化合成反应中,在反应温度200℃、反应时间2H、Ag3PW12O40催化剂用量0.7g和葡萄糖浓度40g.l-1的条件下,乙酰丙酸的最大得率可达到81.61%,催化剂可重复利用。A series of metal-modified heteropolyacid salt catalysts(MXH3-2XPW12O40,M=Zn,Cu,Cs,Ag)were prepared,and the solid heteropolyacid salt Ag3W12O40 was used in hydrolysis of glucose to produce levulinic acid.The surface structures of different heteropolyacid salt catalysts were characterized by means of FTIR,XRD.The surface structures and element relative mass content change of the fresh and used Ag3W12O40 catalyst were also analyzed by means of FTIR,XRD,SEM and EPMA.The effects of such factors as reaction temperature,reaction time,amount of catalyst and glucose concentration on the yield of levulinic acid were investigated.Experimental results showed that the MXH3-2XPW12O40 heteropolyacid salt catalysts kept primary Keggin structure,and Ag3W12O40 catalyst had the structure of Keggin after reuse for several times.It was found that the highest yield of levulinic acid was 81.61%(mole) under the conditions of reaction temperature 200℃,reaction time 2 h,Ag3PW12O40 catalyst dosage 0.7 g and glucose concentration 40 g·L-1.The catalyst could be used repeatedly.国家重点基础研究发展计划项目(2010CB732201);国家自然科学基金项目(U0733001;50776035)---

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