生物甘油化学链吸附强化重整的数值模拟

氢能的高速发展对大规模制氢方式提出了新的要求,生物柴油副产物甘油成为较有前景的制氢原料.基于流体动力学和反应动力学,对流化床生物质甘油化学链重整制氢系统进行模拟研究,分析了反应器内的颗粒和组分分布,考察了操作参数对反应产物的影响.研究结果表明:床层内颗粒呈现明显的稀相区和密相区.反应器底部甘油和水被迅速消耗.温度是影响...     

甘油制氢研究进展

随着生物柴油的规模化发展,如何合理有效利用生产生物柴油过程中的副产物甘油,成为影响生物柴油成本和新一代化学品平台工艺开发的重要问题。甘油作为可再生能源以其分子结构特点可用作制氢的原料。综述了甘油制氢的各种工艺方法,即气相重整(包括水蒸汽重整、部分氧化重整和自热重整)、水相重整、生物法、光催化重整和高温热解等的研究现状,并对未来的发展进行了评述。     

甲烷水蒸汽重整反应制氢催化剂的研究进展

介绍了包括镍基和贵金属基甲烷水蒸汽重整反应制氢催化剂的最新研究进展。分析了催化剂的活性组分、载体和助剂对催化剂的活性和稳定性的影响。最后,对甲烷水蒸汽重整反应制氢催化剂未来的研究方向进行了展望。     

甘油催化重整制氢/合成气的研究进展

随着生物柴油的大规模化发展,副产物甘油的合理利用成为生物柴油产业发展的关键问题之一。对甘油蒸汽重整、水相重整和超临界重整制氢气和合成气的研究进行了综述和评价,对未来甘油重整制氢气/合成气的研究提出了不足和展望。     

生物质多元醇水相重整制氢研究进展

生物质多元醇水相重整是一项正在发展的、很有前景的制氢技术。本文对近些年来涌现的生物质多元醇水相重整制氢研究进行了综述,讨论了多元醇水相重整反应热力学,介绍了反应动力学特征,并以此为基础对反应机理、催化剂体系以及工艺条件优化进行了总结。通过与蒸汽重整对比,指出了水相重整制氢技术的优缺点:优点是能耗低、工艺步骤较少、后处理简单;缺点是副反应多,收率低。最后,提出开发更为高效稳定的催化材料、降低催化剂制备成本和优化工艺条件将是未来研究工作的重点。     

Advances in H2 production from the aqueous-phase reforming of biomass-derived polyols：A review

生物质多元醇水相重整是一项正在发展的、很有前景的制氢技术。本文对近些年来涌现的生物质多元醇水相重整制氢研究进行了综述,讨论了多元醇水相重整反应热力学,介绍了反应动力学特征,并以此为基础对反应机理、催化剂体系以及工艺条件优化进行了总结。通过与蒸汽重整对比,指出了水相重整制氢技术的优缺点：优点是能耗低、工艺步骤较少、后处理简单;缺点是副反应多,收率低。最后,提出开发更为高效稳定的催化材料、降低催化剂制备成本和优化工艺条件将是未来研究工作的重点。     

低温甲醇水重整制氢催化剂研究进展

甲醇具有结构简单、含氢量高、产能大等优点,利用甲醇与水蒸气进行重整是一种节能高效的现场制氢方式。甲醇水蒸气重整(MSR)与燃料电池联用能够实现多场景应用,但由于反应温度较高(250~300℃),存在启动速度较慢、副产CO含量较高和热效率较低等问题。低温甲醇水重整(LT-Methanol Water Reforming, LT-MWR)包括低温甲醇水蒸气重整(LT-MSR)与液相甲醇水重整(Aqueous-phase Reforming of Methanol, APRM),反应通常在200℃以下进行,同时保持较高的反应活性,进而能够减少预热时间、减弱副反应发生,且能与燃料电池实现更强的热耦合。本工作首先介绍了商用催化剂优异的性能与存在的缺陷,然后对低温甲醇水重整制氢催化剂,诸如Cu基催化剂、贵金属催化剂与光协同催化剂的研究进展进行了回顾。归纳了低温铜基催化剂的改性策略,包括合成方法、结构设计与元素掺杂。对国内外商用CuZnAlOx催化剂结构与性能的测试表明,其转化率高和稳定性好,存在的缺陷是价格较贵且在低温区催化活性急剧下降。Cu基催化剂活性受温度影响较大,在低温区活性很低,但通过适当的改性能够实现其应用价值,其改性策略包括合成方法、结构设计与元素掺杂。贵金属催化剂低温下活性较高,但存在价格昂贵、合成复杂等缺点。光协同催化剂则是在光照条件下进行催化重整,尚处于研究阶段。对于Cu基催化剂,合成方法的改进能够大大改善催化剂的微观混合程度与可重现性。适当的结构设计可提升催化剂的比表面积与热稳定性。元素掺杂则能够提升活性组分的分散度,修饰催化剂表面结构。三种改性策略能够有效提升Cu基催化剂低温下甲醇重整制氢的性能,在保持较高活性的同时,降低CO副产物的含量。展望了低温甲醇水重整制氢催化剂的发展前景和挑战,对催化剂的开发与应用有指导意义。     

负载型Pt催化剂的载体对生物油轻质组分水相重整制氢的影响

考察不同载体负载Pt催化剂对生物油轻质组分水相重整(APR)反应的催化性能,并采用X射线衍射(XRD)、透射电子显微镜(TEM)、NH3程序升温脱附(NH3-TPD)、N2低温吸附(BET)和热重(TG)技术对催化剂进行表征。结果表明:较宽的酸强度分布和适量的酸位和较小的Pt颗粒,有利于生物油轻质组分的APR反应制氢;Pt/Al2O3对水相重整反应有较高的催化活性和氢气选择性,10 mL生物油轻质组分和30 mL水在533 K反应4 h后可产生554 mL的气体,其中氢气体积分数可达65%。     

水蒸气重整生物甘油制氢的研究进展

近年来由于世界生物柴油产业的快速发展,生成过剩副产粗甘油,如何有效处置生产过程的粗甘油,已是当前生物柴油产业发展亟待解决的问题.本文对新近出现的以甘油为原料水蒸气重整制氢研究进行了综述,介绍了生物甘油组成与热解性质,总结了国内外水蒸气重整生物甘油及其CO<,2>原位吸附强化重整制氢技术的研究概况,指出吸附强化重整在低温...     

苯酚液相原位加氢合成环己酮和环己醇

基于吸热的甲醇水相重整制氢反应和放热的苯酚液相催化加氢反应使用相同类型的催化剂,比较接近的反应温度和压力,且都在液相状态下进行的特点,提出在Raney Ni催化剂的作用下,将甲醇水相重整制氢反应产生的氢气原位地应用于苯酚加氢合成环己酮和环己醇的反应,实现了水相重整制氢和液相催化加氢两个反应的耦合。消除了传统方法中需要专门的氢气制备、存储和输送等环节,简化了工艺、降低了生产成本。通过这两个反应的耦合,甲醇水相重整过程中甲醇转化率和氢气选择性都得到明显提高;同时,在Raney Ni催化剂[JP2]作用下实现了苯酚的高选择性还原(环己酮和环己醇总选择性达99％以上),比传统的氢气还原法具有更好的效果。     

Revalorization of glycerol: Comestible oil from biodiesel synthesis

High dependence on fossil fuel has caused increase of carbon dioxide concentration in the atmosphere. The actual political trends are towards an increased use of renewable fuels from agricultural origin. One of the main products of the European biorefineries is biodiesel. The main reaction involved in biodiesel synthesis produces a large amount of glycerol as by-product. Two aspects are arising in this respect: the glycerol obtained as residue and the food conversion to fuel. This paper deals with the revalorization of the residual glycerol stream to obtain triacetin (glyceryl triacetate), the lightest comestible oil. The application of glycerol as raw material to produce triacetin is not new. The goal of this paper is to check the feasibility of this transformation in an efficient integrated continuous process which is suitable for processing high quantities of glycerol. A kinetic model was determined experimentally for the production of triacetin from glycerol and acetic acid in the absence of catalyst. The results showed that by process integration of the reaction and distillation in the same unit (reactive distillation), a more sustainable process can be developed. The proposed configuration output is checked by rigorous simulation.     

A review of ionic liquids as catalysts for transesterification reactions of biodiesel and glycerol carbonate production

Biodiesel production has been rapidly increasing due to the strong governmental policies and incentives provided leading to an oversupply of its by-product, glycerol. Therefore, finding ways of utilizing glycerol is essential to increase the net energy and sustainability of biodiesel. Ionic liquids have been used successfully as catalyst for both the production of biodiesel and the conversion of glycerol to glycerol carbonate. These catalysts are relatively environmentally friendly as they have the potential to enable sustainable processes. Herein, the prospect of using ionic liquids to catalyze transesterification triglycerides for the production of biodiesel and the conversion of glycerol to glycerol carbonate will be discussed. Elucidation of the reaction mechanism is expected to provide an in-depth understanding of the process with respect to the effects of cation and anion based on the reactions of interest.     

甘油选择性脱水制备丙烯醛研究进展

生物柴油以其环保性和可再生性而被公认为是可替代石化柴油的新型能源,其迅猛发展将导致其副产物甘油的大量过剩,因此,开发和深度利用甘油,使其成为新一代从生物质到化学品的转化平台成为近期研究热点,其中,甘油脱水制丙烯醛是重要途径。综述了实现该过程的催化剂体系研究进展,探讨了催化剂结构和反应条件对甘油脱水反应性能的影响,分析了甘油脱水的反应路径,以期对开发高性能催化体系和合理工艺提供参考。由于匀相催化剂存在活性低、操作条件苛刻和设备腐蚀等缺点,开发的重点集中在固体酸催化剂上,虽然活性较高,但易失活,稳定性差。仍需进一步提高催化剂性能,同时结合反应器和工艺的设计和选择,综合考量。     

生物柴油副产物甘油产1,3-丙二醇

在生物柴油的生产过程中会产生10%的副产物甘油,随着对生物柴油的大量需求与规模化生产,导致副产物甘油的产量也大幅增加。为了降低生物柴油的生产成本,充分利用副产物甘油是一个非常有效的途径。目前,国内外以甘油为原料通过化学法生产1,3-丙二醇等技术路线已经比较成熟,但其传统化学法存在高温高压操作、释放有毒有害物质等系列问题,而生物催化法以其高产率及高回收率、绿色环保等优势,受到了越来越多的关注。本文主要介绍以甘油为原料,利用生物发酵途径生产1,3-丙二醇的生产技术。     

甘油膜分离-吸附协同强化化学链重整评估

作为生物柴油的副产物,甘油理论氢气产量高,是蒸汽重整的潜在原料。基于化学链技术,结合氢气膜分离和二氧化碳吸附,对甘油化学链重整制氢过程进行热力学模拟研究,分析反应器操作压力和膜渗透侧压力的改变对氢气产量和系统热量需求的影响。结果表明,反应器压力的提高和渗透侧压力的降低可以有效的增强氢气产量,抑制甲烷的生成,系统的反应热对压力的变化并不敏感,而吸附剂甘油比的提高能够提高重整所需的热量,进而实现系统的自热。     

Biodiesel production using immobilized enzyme-current state and future perspective

近年来由于化石燃料的全球性短缺、原油价格的过度上涨和环境问题的加剧致使生物柴油的生产迅速增长。生物柴油生产的关键反应是化学或生物催化的转酯反应,酶催化的转酯反应与化学催化相比有相对节能、副产物甘油易回收及适合高含量游离脂肪酸油脂作为底物等明显优势。本文综述了固定化脂肪酶生产生物柴油的现状及最新进展,包括生物柴油的原料、脂肪酶的来源、酶的固定化技术、甲（乙）醇及甘油对脂肪酶的失活作用,展望了固定化脂肪酶生产生物柴油的未来前景。     

碳酸甘油酯的合成研究及产业化进展

碳酸甘油酯是一种颇具吸引力的高附加值甘油衍生物,研究以甘油为反应底物制备高附加值的碳酸甘油酯,已成为实现生物柴油副产物甘油综合利用的有效途径之一。本文简述了包括光气法、CO氧化羰化法、酯交换法、尿素醇解法、CO ₂转化法等在内的碳酸甘油酯合成方法,总结了现有碳酸甘油酯合成的主要催化剂及催化合成反应机理,并简要介绍了我国原料甘油市场现状及国内外碳酸甘油酯合成的产业化进展。最后,从技术研发和产业化发展两个方面对碳酸甘油酯合成的未来发展进行了展望,指出一方面应在开发具有高性能催化剂的同时注重催化基础理论的研究,另一方面应在优化工艺流程、降低产品成本的同时注重下游产业应用与替代,并提出我国应推进生物柴油副产物甘油合成碳酸甘油酯的规模化生产与应用示范,加快培育具有国际竞争力的生物质能源与废弃物资源化利用产业。     

New process for catalyst-free biodiesel production using subcritical acetic acid and supercritical methanol

The production of glycerol as a by-product is unavoidable in the current conventional biodiesel manufacturing processes. Since biodiesel production is expected to increase in the near future, effective utilization of glycerol will become an issue of interest. In this study, therefore, a process consisting of subcritical acetic acid treatment to convert rapeseed oil to fatty acids and triacetin followed by conversion of the obtained fatty acids to their fatty acid methyl esters in supercritical methanol treatment was investigated. The obtained results clearly revealed that this two-step reaction could proceed effectively at a high reaction rate, and that fatty acid methyl esters and triacetin could be obtained under milder reaction condition than the one-step process utilizing supercritical methyl acetate and supercritical methanol.     

Hydrogen Production from Glycerol Over Nickel Catalysts Supported on Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Modified by Mg,Zr, Ce or La

Hydrogen production from glycerol reforming in liquid (aqueous phase reforming, APR) and vapor (steam reforming SR) phase over alumina-supported nickel catalysts modified with Ce, Mg, Zr and La was studied. Characterization of catalysts by temperature programmed reduction and XPS analyses revealed important structural effects: (i) the intercalation of Mg between nickel and alumina that inhibited the alumina incorporation to nickel phases, (ii) the close contact between Ni and Zr phases and, (iii) the close surface interaction of La and Ce ions with NiO phases. The catalytic activity of the samples studied in this work clearly indicated the different catalyst functionalities necessary to carry out aqueous-phase and vapor-phase steam reforming of glycerol. For aqueous phase reforming of glycerol, the addition of Ce, La and Zr to Ni/Al₂O₃ improves the initial glycerol conversions obtained over the Ni/Al₂O₃ supported catalyst. It is suggested that the differences in catalytic activities are related with geometric effects caused by the decoration of Ni phases by Ce and La or by the close interaction between Ni and Zr. In spite that nickel catalysts showed high APR activities at initial times on stream, all samples showed, independently of support, important deactivation rates that deactivate the catalysts after few hours under operation. Catalysts characterization after APR showed the oxidation of the active metallic Ni during reaction as the main cause of the observed deactivation. In the case of the glycerol steam reforming in vapor phase, the use of Ce, La, Mg and Zr as promoters of Ni based catalysts increases the hydrogen selectivity. Differences in activity were explained in terms of enhancement in: surface nickel concentration (Mg), capacity to activate steam (Zr) and stability of nickel phases under reaction conditions (Ce and La).