纳米催化剂在生物柴油合成中的应用

生物柴油作为一种可再生的绿色能源,是化石燃料理想的替代品。本文聚焦于纳米催化剂在生物柴油合成中的应用,就常见的纳米催化剂的设计制备、物化性质、催化行为及重复使用性等方面进行了综述,最后提出了纳米催化在生物柴油合成中所面临的问题并展望其应用前景。     

生物柴油制备中酸化油酯化反应的研究

生物柴油因具有易降解、可再生、燃烧性能高等优良特性得到了广泛的应用。在实际生产及推广应用中,以酸化油为原料合成生物柴油,可大大降低生产成本。催化剂的性能是合成生物柴油的关键,主要概述了催化剂在酸化油酯化反应合成生物柴油中的研究进展,并展望了生物柴油的发展前景。     

离子液体在生物柴油合成中的应用研究进展

离子液体具有较强的催化能力、较强的溶解能力、较低的蒸气压等特性,其在生物柴油合成中的应用近年来受到人们的持续关注。本文介绍了离子液体不仅可作为酶催化合成生物柴油的绿色溶剂,作为酯交换反应合成生物柴油的催化剂,还可作为催化剂载体,并可以实现离子液体在生物合成应用中的循环利用。提出了今后应加强对离子液体中固定化脂肪酶催化合成生物柴油的传质过程和催化作用机制及离子液体的循环利用进行研究。     

磁性纳米催化剂制备生物柴油研究进展

磁性纳米催化剂是一类具有磁响应特征的催化剂,由于具有较高的催化活性、良好的反应选择性及优良的磁响应性等优点,克服了纳米催化剂活性高但难分离的缺点,是生物柴油制备过程良好的甲酯化反应催化剂,为生物柴油催化剂研究的重要方向。本文综述了磁性纳米催化剂的结构特点、制备方法及其在制备生物柴油过程中的应用,并展望了其应用前景。     

多相纳米催化剂制备生物柴油的研究进展

介绍了国内外多相纳米催化剂用于制备生物柴油的最新进展,归纳总结了不同多相纳米催化剂的类型、优缺点及催化制备生物柴油的研究现状,分析了多相纳米催化剂催化制备生物柴油过程中存在的问题,进而对今后的研究方向和应用做出展望。     

离子液体在合成生物柴油中的应用

酯交换反应是合成生物柴油的最主要方法,反应中常用到有机及无机溶剂,鉴于传统溶剂对环境的污染,离子液体作为新型环保溶剂成为更好的选择。介绍离子液体的特性及其作为催化剂、酶溶剂及催化剂载体在合成生物柴油中的应用。     

离子液体催化制备生物柴油研究进展

生物柴油由于具有环保、可再生、良好的润滑性与稳定性等优良特征,已逐渐成为汽油、柴油等传统石化燃料的替代品。目前,生物柴油的制备过程中所采用的催化剂多为固体酸碱、液体酸碱等传统非均相与均相催化剂,虽然可以得到较高收率的生物柴油,但此类传统催化剂在使用过程中会造成设备腐蚀、废水处理等与环境、经济相关的问题。离子液体因具有结构可设计性、不易挥发、良好的化学稳定性、无污染以及易回收等优点,可作为一种应用于生物柴油制备的新型高效绿色环保催化剂。结合近几年离子液体在生物柴油合成领域的最新研究,综述了不同种类离子液体催化制备生物柴油的应用进展。     

离子液体介质中催化合成生物柴油技术研究

生物柴油作为一种可替代再生性清洁能源,成为新能源领域研究和开发的热点之一.廉价的原料、新合成工艺和高效催化剂技术是降低生产成本,促使该项技术推广应用的发展方向.离子液体作为一种功能可设计的新型绿色溶剂和催化剂,在化学反应和过程开发中显示出了独特的应用前景.将离子液体用于生物柴油制备是近年来新发展的方向,回顾了离子液体在...     

固定化酶及全细胞生物催化合成生物柴油的研究进展

生物柴油是一种可再生的绿色环保型能源.酶法合成生物柴油具有条件温和、醇用量小、甘油易回收等优点.本文综述了固定化脂肪酶、全细胞生物催化剂在生物柴油制备中研究应用的新进展.     

固体碱催化酯交换反应制备生物柴油研究进展

介绍了非负载型和负载型2类固体碱催化剂用于制备生物柴油的研究进展,采用酯交换法因其无需消耗大量能量、操作方法简单,成为制备生物柴油的主要方法,并随着负载型固体碱催化剂载体的纳米化、介孔化,纳米级以及以分子筛作为载体的固体碱催化剂将成为一个主要的研究方向。认为开发更加稳定、耐水、耐酸的固体碱催化将是今后固体碱催化剂的研究重点。     

Immobilization of nanocatalysts on cordierite honeycomb monoliths for low temperature NOx reduction

Noble metal nanocatalysts such as Pd, Pt, and Au were strongly immobilized on the inside walls of monolithic honeycomb-structured cordierite, in which bi-functional molecules were used as linkers for anchoring noble metal nanoparticles (NPs) on the cordierite surface. The supported nanocatalysts were characterized by ICP-MS, TEM, and X-ray powder diffraction. The efficiencies of the immobilized nanocatalysts for the removal of harmful nitrogen oxides (NO_x) have been investigated by measuring the deNO_x capability as a function of temperature. The catalytic activities depend mainly on the compositions of the nanocatalysts. The Pd/Pt bi-metal catalyst anchored on the cordierite surface shows higher NO_x conversion and better activity than the commercial emission catalyst at low temperature region, which could be due to the large portion of active surface areas of the catalysts with nanometer scale.     

Olefin epoxidation with metal-based nanocatalysts

Alkene epoxidations are an important class of reactions carried out in industry; however, current methods are plagued by problems, including high cost, difficulty in recovering catalysts, and generation of large quantities of acidic and chlorinated waste. In recent years, nanocatalysts have been considered as robust, heterogeneous alternatives to homogeneous catalysts. This work evaluates silver- and base metal-containing nanocatalysts as olefin epoxidation catalysts, highlighting the industrial applicability and green aspects of these catalytic systems. The nanocatalysts discussed are mostly supported or composite materials that showed (generally) good activity and selectivity for various/multiple olefin epoxidation reactions.     

A comparative study of Pt and Pt–Pd core–shell nanocatalysts

This comparative study characterizes two types of metallic and core–shell bimetallic nanoparticles prepared with our modified polyol method. These nanoparticles consist of Pt and Pt–Pd core–shell nanocatalysts exhibiting polyhedral morphologies. The controlled syntheses of Pt metallic nanoparticles in the 10-nm regime (4–8 nm) and Pt–Pd bimetallic core–shell nanoparticles in the 30-nm regime (15–25 nm) are presented. To realize our ultimate research goals for proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs), we thoroughly investigate the dependence of the electrocatalytic properties of the nanoparticles on the structure, size and morphology. Significant differences in the electrocatalysis are also explained in experimental evidences of both Pt and Pt–Pd nanocatalysts. We suggested that the core–shell controlled morphologies and nanostructures of the Pd nanoshell as the Pd atomic monolayers will not only play an important role in producing inexpensive, novel Pt- and Pd-based nanocatalysts but also in designing more efficient Pt- and Pd-based nanocatalysts for practical use in DMFC technology. Our comparative results show that Pt–Pd nanocatalysts with Pd nanoshells exhibited much better electrocatalytic activity and stabilization compared to Pt nanocatalysts. Interestingly, we found that the size effect is not as strong as the nanostructuring effect on the catalytic properties of the researched nanoparticles. A nanostructure effect of the core–shell bimetallic nanoparticles was identified.     

Preparation of Co–Mo supported multi-wall carbon nanotube for hydrocracking of extra heavy oil

In this study, multi-wall carbon nanotube (MWCNT) supported Co–Mo nanocatalysts with changes in synthesis steps, one and two-step, were prepared through impregnation to be used in extra heavy oil hydrocracking process. In both of the synthesized nanocatalysts, the Co/Mo weight ratio was 1/3. The nanocatalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and accelerated surface area and porosimetry (ASAP) methods. The results showed that the nanocatalysts prepared through a two-step impregnation method had higher surface area and pore volume than the other synthesized nanocatalysts.The nanocatalysts were used in hydrocracking process under mild operating conditions, 260–300 °C and at H₂ initial pressure of 5 MPa. Hydrocracking of extra heavy oil was conducted in an autoclave reactor. The results indicated that both nanocatalysts were capable of hydrocracking heavy oil at mild operating conditions. However, the nanocatalysts synthesized through the two-step impregnation exhibited higher performance, better heavy oil to light oil conversion, and better sulfur removal than the other methods. This superiority is due to the nanocatalyst's structure and better distribution of metal clusters on the support.     

催化剂制备与研究热解温度对自模板法制备纳米催化剂催化活性的影响

金属有机骨架材料(MOFs)作为典型的自模板材料已被广泛应用于催化、电化学和吸附等领域。采用水热法合成两种含氮的Co-Ni-MOF和Co-Cu-MOF材料,并以两种材料为模板剂,在不同温度热解制备Co-Ni@NC和Co-Cu@NC纳米催化剂。将两种纳米催化剂用于乙基苯选择性氧化制备苯乙酮反应, 研究热解温度对催化剂催化活性的影响。结果表明,随着热解温度升高,催化活性逐渐增强,当热解温度达到900 ℃时,催化活性最高,苯乙酮收率为98%~99%,催化剂还表现出较好的重复使用性能。     

Synthesis and Characterization of Pt/C Nanocatalysts Using Room Temperature Ionic Liquids for Fuel Cell Applications

Carbon supported Pt nanocatalysts are prepared using different room temperature ionic liquids (RTILs) as the solvent and conventional preparation techniques, based on wet impregnation methods. The Pt/C nanocatalysts are characterized by XRD, TEM, EDX, and XPS. The results of the analyses show that the Pt/C catalysts, using different RTILs as solvents, are homogeneously dispersed with a narrow size distribution. The electro‐oxidation of liquid methanol on these catalysts is investigated at room temperature by cyclic voltammetry and chronoamperometry. The results have shown that the Pt/C catalysts prepared using RTILs are more active than the other Pt/C catalysts prepared by the authors. Surface area measurements of the Pt metal, conducted by electro‐oxidation of preadsorbed CO, indicate that catalysts prepared using RTILs as the solvents have higher surface area. The Pt/C nanocatalysts, prepared using RTILs, exhibit enhanced activity for the methanol oxidation reaction, compared with the Pt/C catalysts prepared by the impregnation method and commercial Pt/C catalysts.     

Nanostructured metallopolymer catalysts in fine organic synthesis

The article presents results of the synthesis of the nanocatalysts formed in the nanostructured polymeric environment and their properties. These nanocatalysts were analyzed in the reactions of selective hydrogenation and oxidation, which are the basic stages of synthesis of vitamins and aromatic compounds. The amphiphilic block copolymer micelles, ultrathin layers of polyelectrolytes and the nanopores of hypercrosslinked polymers were used as nanostructured polymeric matrices. The formation and properties of both mono- (Pd, Pt) and bimetallic (PdPt, PdAu, PdZn) nanoparticles stabilized by polymers were considered. The efficiency of nanocatalysts in combination with the high stability makes them easy to produce and promising for industrial application.     

Low-temperature efficient degradation of ethyl acetate catalyzed by lattice-doped CeO2–CoOx nanocomposites

A series of CeO₂–CoO_x nanocatalysts have been synthesized by a facile surfactant-free hydrothermal method and investigated for the oxidative degradation of ethyl acetate (EA) at exceptionally low temperature. The combination of various techniques, such as H₂-TPR, XRD, XPS and HRTEM provides insights to the effect of various factors including redox properties, enhanced lattice oxygen and its mobility etc. on catalysis performance. The results demonstrate that the enriched lattice oxygen is the dominant factor for the low-temperature degradation of EA due to the interaction between lattice-mixed Ce and Co ions, which can be used to design the catalysts for removing VOCs with improved performance.     

Hollow mesoporous silica spheres supported Ag and Ag–Au catalyzed reduction of 4-nitrobenzo-15-crown

Hollow mesoporous silica (HMS) spheres of size within the range 120–220 nm have been prepared using propanol–water solvent as template and cetyltrimethylammonium bromide (CTAB) as stabilizer. HMS supported silver and silver–gold catalysts were prepared by impregnating metal nanoparticles on HMS and were characterized by ultraviolet–visible spectroscopy (UV–vis), dynamic light scattering (DLS), optical microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), inductive coupled plasma optical emission spectroscopy (ICP-OES) and N₂ adsorption–desorption. The reduction of 4-nitrobenzo-15-crown (4-NB-15-C) was compared using HMS supported silver and silver–gold nanocatalysts varying experimental parameters. Bimetallic Ag–Au/HMS nanocatalysts was found to be more active than monometallic Ag/HMS nanocatalyst.