生物质转化中的加氢脱氧反应及其催化剂研究

发布时间：2018-02-20 15:13

本文关键词： 生物质加氢脱氧催化剂 5-羟甲基糠醛乙酰丙酸酚类燃料　出处：《中国科学技术大学》2017年博士论文　论文类型：学位论文

【摘要】：人类对于能源的需求不断增加、不可再生的化石资源的日益枯竭以及随之产生的温室效应、大气污染等问题的出现,迫使人们探索绿色可再生的新能源。生物质资源是目前唯一可再生的有机碳资源,具有量大、分布广泛、廉价易得等特点,引起学术界和产业界的广泛关注,并被认为具有替代化石资源提供化学品和燃料的潜力。发展基于生物质的高附加值化学品和液体燃料,不仅可以解决当前生物质不合理使用对环境和人类健康带来的威胁,而且还实现了废物再利用,提高整体产业链的附加值,促进农民增收,推动我国农业现代化建设。生物质主要分为纤维素、半纤维素和木质素三大组分,纤维素是由葡萄糖通过β-1,4-糖苷键聚合形成的高分子,半纤维素是由五碳糖、六碳糖聚合形成的高分子,木质素主要是由香豆醇、松柏醇和芥子醇三种结构构成,比较复杂,较难解聚。对生物质进行酸水解可以得到六碳糖、五碳糖的水解液以及木质素残渣。六碳糖通过催化脱水可以转化为平台化合物5-羟甲基糠醛和乙酰丙酸,五碳糖经催化转化可转化为平台化合物乙酰丙酸,木质素经催化降解可以得到一系列酚类衍生物。5-羟甲基糠醛、乙酰丙酸和酚类衍生物经催化加氢脱氧可转化为2,5-二甲基呋喃、γ-戊内酯和环烷烃用作液体燃料,对于发展可再生生物能源具有重要意义。然而,目前已有的催化剂还存在较多问题,如催化剂反应活性差、选择性低、催化剂制备复杂、反应条件苛刻、循环性能低等。因此,发展高活性高选择性的新型催化剂体系用于以上加氢脱氧过程,实现在温和条件下高效转化为相应的液体燃料分子非常重要。针对以上过程,本论文设计了一系列易于制备、高活性、低成本的催化体系,通过对催化剂合成的调节实现对产物分布的调控,论文主要分为以下四个部分:在第1章,介绍了生物质的组成、结构以及生物质利用情况。接着重点对生物质基5-羟甲基糠醛、乙酰丙酸和酚类衍生物的合成以及加氢脱氧转化为液体燃料和化学品的研究进展进行介绍。在第2章,介绍了钙钛矿型氧化物负载Ni催化剂催化5-羟甲基糠醛氢解制备2,5-二甲基呋喃。采用柠檬酸络合法制备了钙钛矿负载不同Ni含量的催化剂,发现LF-N20催化剂可以实现5-羟甲基糠醛以98.3%的产率转化为2,5-二甲基呋喃。考察了反应温度、氢气压力对反应结果的影响,催化剂循环使用5次依然保持较高的反应活性,根据动力学实验及中间体实验提出可能的反应机理。在第3章,介绍了商业分子筛负载Pt催化剂催化乙酰丙酸乙酯制备γ-戊内酯的过程。采用浸渍法将Pt负载在一系列商业分子筛上,将其用于乙酰丙酸乙酯还原制备Y-戊内酯的过程,发现以Pt/ZSM-35在200 ℃C下可以得到99%的γ-戊内酯的产率,考察了反应温度、氢气压力和反应溶剂对于反应结果的影响。并结合XRD、XPS、TEM和BET分析探索催化剂的微观结构与反应结果之间的关系。最后研究了催化剂的稳定性,催化剂使用3次后反应活性略微降低。在第4章,介绍了双相体系中碳纳米管负载Ru催化木质素衍生酚类化合物加氢脱氧制备烷烃的过程。传统的酚类衍生物加氢脱氧过程通常是在单相溶剂体系进行的,采用双相溶剂体系可以使在水相发生了加氢脱氧反应后生成的环烷烃快速进入有机相,从而避免了进一步发生C-C键断裂而导致产率的降低。本章采用浸渍法合成了 Ru/CNT,其在水/正十二烷的双相体系中实现了丁香酚以94%的产率得到丙基环己烷,而在单相水体系中产率仅为56.5%,在正十二烷溶剂中产率仅为4%,这也印证双相体系的优势。这种双相催化体系中,木质素衍生的酚类单体和二聚体都可以加氢脱氧得到相应的烷烃。这种双相体系的使用也拓展了生物质加氢脱氧的新思路。综上所述,本论文主要以生物质衍生的重要化合物为研究对象,设计了不同的催化体系实现了这些化合物高效的发生加氢脱氧转化为相应的目标产物,并且催化剂都可以循环使用。结合催化剂的表征,研究了不同催化剂的结构与反应的活性和选择性之间的关系,发展的这些催化体系也促进生物质的催化转化和应用。
[Abstract]:The human demand for energy is increasing, the non renewable fossil resources are depleted and the resulting greenhouse effect, air pollution and other problems arise, forcing people to explore new energy green renewable biomass resources. Is currently the only renewable carbon resource, has large quantity, wide distribution, cheap etc. caused widespread concern in academia and industry, and is thought to be a substitute for fossil fuels and chemical resources potential. The development of high value-added chemicals and liquid fuels based on biomass, biomass can not only solve the current unreasonable use brings threat to the environment and human health, but also realize the reuse of waste, improve the added the value of the whole industry chain, increase farmers' income, promoting agricultural modernization of our country. The biomass mainly consists of cellulose, hemicellulose and lignin in three major components , cellulose is composed of glucose by -1,4- beta glycosidic bond polymerization to form the polymer, hemicellulose is composed of five carbon sugar, six carbon sugar polymerized to form polymer, lignin is mainly composed of p-coumaryl alcohol, coniferyl and Sinapyl alcohol, three kinds of structure is more complex and difficult. The biological depolymerization of hyaluronic acid hydrolysis can get six sugar, five carbon sugar hydrolysis and lignin residue. By catalytic dehydration can be transformed into six carbon platform compound 5- hydroxymethyl furfural and levulinic acid, five carbon sugar by catalytic conversion into levulinic acid by catalytic degradation of lignin, we can get a series of phenol derivatives.5- hydroxymethyl furfural, levulinic acid and phenol derivatives by catalytic hydrogenation deoxidation can be transformed into 2,5- two methylfuran, gamma valerolactone and cycloalkanes used as liquid fuel, is very important for the development of renewable energy. However, at present The catalyst also has many problems, such as catalytic activity, low selectivity, catalyst preparation complex, harsh reaction conditions, low cycle performance. Therefore, a new catalyst system for the development of high activity and high selectivity for the hydrogenation deoxidation process, achieved under mild conditions, conversion to liquid fuel molecules is very important. According to the above process, this paper designed a series of easy preparation, high catalytic activity, low cost of system, by adjusting the catalyst for the synthesis of regulation of product distribution, this paper is mainly divided into the following four parts: in the first chapter, introduces the structure and composition of biomass, biomass utilization situation and then focus on. Biomass based 5- hydroxymethyl furfural, progress in the synthesis of levulinic acid and phenol derivatives and study of hydrodeoxygenation into liquid fuels and chemicals were introduced in second. Chapter, introduces the perovskite type oxide catalyst 5- catalyst Ni hydroxymethyl furfural hydrogen preparation of 2,5- two methylfuran system solutions. Load different content of Ni perovskite type were prepared by citric acid method, found that LF-N20 catalyst can achieve 5- HMF in 98.3% yield to 2,5- two methylfuran were investigated. Influence of temperature, hydrogen pressure on the reaction results, the catalyst was recycled 5 times still maintain high reactivity, according to the dynamic experiment and intermediate experiment put forward the possible reaction mechanism. In the third chapter, introduces the commercial molecular sieve catalyst preparing gamma valerolactone acetyl ethyl propionate Pt catalyst by impregnation method. The preparation process of Pt the load in a series of commercial molecular sieve, the process for preparing Y- valerolactones levulinic acid ethyl ester reduction, found by Pt/ZSM-35 at 200 DEG C can be obtained under 99% gamma valerolactone The yield, the effects of reaction temperature, hydrogen pressure and solvent effects on the reaction. Combined with XRD, XPS, TEM and BET analysis of the relationship between the microstructure and the reaction results of the catalysts. The study explored the stability of the catalyst, the reaction activity decreased slightly after 3 times of catalyst. In the fourth chapter, introduced. The process of two phase system of Carbon Nanotubes Supported Ru catalyst preparation of alkanes in lignin derived phenolic compounds hydrodeoxygenation of phenol derivatives. The hydrodeoxygenation process is usually carried out in the traditional single-phase solvent system, using double phase solvent system can make the cyclane happen hydrodeoxygenation reactions in the aqueous phase after the generation of quick access the organic phase, so as to avoid further cleavage of C-C and lead to yield reduction. This chapter Ru/CNT was synthesized by impregnation method, the water / double phase system is implemented in the twelve - to eugenol 94% the yield of propyl cyclohexane, and in single-phase water system which was only 56.5% in twelve, alkane solvent yield is only 4%, which also confirms the two phase system. The advantages of this biphasic catalytic system, phenolic lignin derived monomers and two dimers can get the corresponding hydrodeoxygenation the use of the alkane. Two phase system also extends the new idea of biomass hydrodeoxygenation. To sum up, this paper focuses on the important compounds of biomass derived as the research object, design the different catalytic system realizes these compounds efficiently occurred hydrodeoxygenation into the corresponding target product, and the catalyst can be recycled with the characterization of catalyst, the study of the relationship between the structure and reaction of different catalyst activity and selectivity, the development of these catalytic systems also promote catalytic conversion and application of biomass.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O643.36;TK6

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