中国科学院机构知识库网格
Chinese Academy of Sciences Institutional Repositories Grid
锆基超稳多孔材料的功能化、表征和催化/吸附应用研究

文献类型:学位论文

作者LATIF ULLAH
答辩日期2019-07-01
文献子类博士
授予单位中国科学院大学
导师张香平
关键词锆基多孔材料,杂多酸,纳米颗粒,异相催化,脱硫
学位专业应用化学
英文摘要

催化/分离科学技术的发展对国民经济社会的可持续发展至关重要,其核心是开发清洁高效经济稳定的高性能催化剂/吸附剂。近年来,锆基多孔功能材料因具有稳定性高、比表面大、环境友好而且易于功能化修饰等特性在众多新型催化/吸附材料中备受关注。此外材料的组成、微观结构与形貌决定其催化/吸附性能,而材料的组成、微观结构与形貌又与合成方法与结晶过程密不可分。因此本论文探索了多种策略合成超稳锆基功能多孔材料以及其在付克酰基化、铃木交叉耦联反应吸附脱硫及催化氧化深度脱硫中的应用,系统深入地研究了材料合成-结构-性能多层次的构效关系,取得了系列创新性成果,具体介绍如下:(1). 采用溶剂热一锅法直接合成了高比表面积(1065-2058 m2/g)和高磷钨酸(HPW)负载量(32.3 wt.%)的酸性锆基功能MOF材料(HPW@Zr(BTC)。研究表明适量HPW的引入不仅在合成过程中起到模板作用提高了锆基MOF材料的结晶度和热稳定性而且赋予其超强酸的酸性。该功能材料在苯甲酰氯与茴香醚的付克酰基化反应中展现了良好的催化活性,其中HPW负载量为28.2 wt.% 的HPW@Zr(BTC) 催化活性最好,苯甲醚的转化率可达99.4%,对甲氧基二苯甲酮的收率可达97.9%,而且催化剂至少可连续循环使用五次。(2). 开发了一种调制剂辅助合成大尺寸高稳定Zr-BTC晶体的方法,基此采用三种策略合成了纳米钯负载的锆基功能材料(Pd@Zr(BTC), (c) Pd-PVP/Zr(BTC), (d) Pd/Zr(BTC)),该材料在溴化苯和苯并硼酸的铃木交叉耦联反应中展现了良好的催化活性。其中采用调制剂辅助的溶剂热一锅法合成的Pd@Zr(BTC) 催化性能最佳,在温和反应条件下,联苯收率大于97.2%,而且该催化剂在多次循环使用过程中无纳米钯颗粒聚集保持较高的催化活性。(3). 燃料脱硫是现阶段节能减排和环境保护的重要措施。吸附脱硫是一种较为经济的燃料脱硫手段。在本文中,采用后功能修饰方法合成了HPW/Zr(BTC) 酸性材料用于燃料吸附脱硫的研究,并采用非线性Langmuir吸附模型和范特霍夫吸附热模型对苯并噻吩的吸附脱除行为进行描述。研究表明,HPW的质子酸性位点和Zr-BTC的路易斯酸性位点的协同作用极大提高了功能材料对苯并噻吩的吸附脱除,其中HPW(1.5)/Zr(BTC) 最大吸附容量可达290 mg.g-1高于Zr-BTC(238 mg.g-1),和目前报道的最好吸附剂的吸附容量相当。(4). 含硫化合物的催化氧化降解是燃料深度脱硫的一种有效途径。采用溶胶-凝胶水热法一步合成了负载磷钼钒酸(PMV)和钯纳米粒子的双功能催化剂(Pd-PMV/MZrO2),用于模型燃料中二苯并噻吩(DBT)和苯并噻吩(BT)的催化氧化脱硫。以叔丁基过氧化氢(TBHP)为氧化剂,在温和反应条件下, DBT和BT转化率分别为 >99.0%和97.7%而且催化剂至少可重复使用10次。Pd-PMV/MZrO2功能材料合成简单、易规模制备、催化活性高且稳定性好,是一种具有工业化应用前景的燃料深度氧化脱硫的双功能催化剂。 ;In recent years, stricter environmental regulations in China and elsewhere have forced the scientific community to find alternatives to the conventional catalysts and adsorbents. Therefore, development and fabrication of stable, economically viable and environmentally benign functional porous materials with large surface area, have recently received much attention. Zirconium-based porous materials due to their thermochemical stability, environmentally benign stature and economic viability, have the potential to meet the modern-day challenges. In this work, we developed different strategies for synthesis and modification of Zr-based porous materials for heterogeneous catalytic and adsorptive applications. The effect of heteropoly acid or noble-metal (in this case Pd) on the physico-chemical traits of the host material were explored. The original innovative works are summarized as:(1) Development of novel hybrid catalyst HPW@Zr(BTC), composed of phosphotungstic acid (HPW) and Zr-MOF, via one-pot direct solvothermal synthesis method. High HPW loading (up to 32.3 wt.%) was achieved. Characterization of the composite catalyst proved that the crystalline morphology and thermostability of Zr(BTC) was enhanced by HPW up to a threshold wt.% loading. The catalytic activity of the hybrid composite was explored via Friedel-Crafts acylation of anisole with benzoyl chloride. The 28.2 wt.% HPW@Zr(BTC) showed excellent catalytic performance, with 99.4% anisole conversion and 97.9% yield (p-methoxybenzophenone) under solvent free conditions. Excellent retention of catalytic activity was achieved after at least five consecutive runs due to non-observable HPW leaching. The promising activity and stability of the catalyst forecasted its potential industrial applications.(2) The work describes synthesis of Pd-impregnated Zr-MOF, as heterogeneous catalysts for Suzuki-Miyaura cross-coupling reactions. Different co-modulated synthesis strategy was used to synthesize stable large MOF crystals. The catalysts showed excellent catalytic activity in H2O:EtOH solvent, achieving 97.2% yield of biphenyl, with cross-coupling of phenyl bromide and benzoboronic acid at relatively mild reaction conditions. The best performance was achieved by Pd@Zr(BTC) catalyst, prepared by a one-pot solvothermal method. The catalyst was reusable for multiple runs maintaining its efficiency. (3) The work reports on the adsorptive removal of benzothiophene from liquid fuel using a highly porous metal-organic framework based on a bicomponent zirconium benzene-tricarboxylate, and its post-synthetically modified hybrid form with dodeca-tungstophosphoric acid (HPW/Zr(BTC). Temperature and concentration dependent BT adsorption data were in good agreement with the non-linear Langmuir model combined with van’t Hoff description of the heat of adsorption. The maximum predicted adsorption capacities were estimated to be 290 and 238 mg.g-1 for HPW(1.5)/Zr(BTC) and Zr(BTC) comparable to the contemporary reported adsorbents. Although the highly porous Zr(BTC) had good adsorptive sites, its adsorption capacity was further enhanced by incorporation of HPW. This was attributed to the synergistic effect of active acid sites provided by HPW and the open metal-sites on the Zr(BTC) framework. (4) A novel bifunctional catalyst, consisting of palladium metal and molybdovanadophosphoric acid (PMV) supported on mesoporous zirconia, was developed for catalytic oxidative desulfurization of dibenzothiophene (DBT) and benzothiophene (BT) from model fuel. Up to a threshold PMV loading, the mZrO2 revealed improved stability, while the hybrid catalysts had both Br?nsted and Lewis acidic sites. The oxidative desulfurization abilities of xPMV/mZrO2 were further enhanced with Pd-promotion, achieving with >99.0% and 97.7% for DBT and BT conversion. Catalyst was reusable, and high catalytic activity was maintained over 10 cycles, making it a promising bifunctional catalyst for oxidative deep desulphurization of liquid hydrocarbon fuels. 

语种英语
源URL[http://ir.ipe.ac.cn/handle/122111/40643]  
专题中国科学院过程工程研究所
推荐引用方式
GB/T 7714
LATIF ULLAH. 锆基超稳多孔材料的功能化、表征和催化/吸附应用研究[D]. 中国科学院大学. 2019.

入库方式: OAI收割

来源:过程工程研究所

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