简析气相聚乙烯催化剂发展进程

简述了各种气相聚乙烯催化剂的国内外发展状况,包括铬系催化剂、齐格勒-纳塔催化剂、茂金属催化剂、后过渡金属催化剂、双功能催化剂和复合催化剂等。     

催化剂再生装置在化工厂的应用分析

催化剂是化工生产中的重要生产原料,催化剂的利用效率直接影响着化工生产的成本控制和产品质量。催化剂再生是当前提升催化剂使用效率的主要方式,通过催化剂再生技术手段和响应的再生装置可以不同程度的恢复催化剂活性。本文概述了催化剂再生技术的分析原理,并对当前主要的催化剂再生装置进行了简要分析,并探讨了催化剂再生装置在化工产的应用现状。     

生物柴油制备中固体碱催化剂的研究进展

主要综述了几种负载型催化剂和非负载型催化剂,如分子筛固体碱催化剂、阴离子交换树脂催化剂、碱金属固体催化剂、CaO有关的固体碱催化剂及Al2O3作为载体的固体碱催化剂,分别对它们进行了总结并提出展望,其中可持续发展的绿色催化剂将成为今后的研究热点。     

DBHFC阴极铂合金催化剂的制备及其电催化性能

采用浸渍还原法分别制备了两种不同铂含量的Pt/C纳米催化剂和Pt-Mn/C、Pt-Co/C纳米合金催化剂,利用XRD和TEM技术对催化剂的粒径大小、晶体结构和晶格常数进行表征,并对四种催化剂进行了循环伏安、线性扫描伏安和电流-时间测试。结果表明:四种催化剂的平均粒径均在10nm以下,且Pt-Mn/C、Pt-Co/C两种合金催化剂的粒径均小于Pt/C催化剂;四种催化剂均为面心立方晶体结构;与Pt/C催化剂相比,两种合金催化剂的晶格常数有所减小,且结晶度较低。电化学性能测试表明,两种Pt合金催化剂较相同Pt载量的纯Pt催化剂具有更高的还原峰电位和更大的还原峰电流,其中Pt-Co/C催化剂的还原峰电位和峰电流最大;在催化剂稳定性方面,两种Pt合金催化剂要优于两种纯Pt催化剂。     

用于稠油降粘的水热裂解催化剂研究进展

为了解决稠油开采的难题,如今越来越多的研究聚焦在稠油降粘技术上,应用催化剂来提高稠油降粘效率是一种永久性的原位升级方法。综述了近年来国内外报道的各种催化剂类型,包括无机酸盐催化剂、有机盐催化剂、矿物催化剂、无机酸催化剂和金属基纳米催化剂,描述了它们在稠油地下催化裂解中的有效性,并展望了水热裂解催化剂的应用前景。     

钯催化剂在燃料电池阳极中的研究进展

钯(Pd)作为燃料电池阳极催化剂,具有重要的市场应用前景。从纯Pd催化剂,负载型Pd催化剂,Pd基合金催化剂3个方面综述了近年来Pd催化剂在燃料电池阳极中的研究进展,介绍了其结构形态、载体、掺杂元素等对Pd催化剂的催化性能的影响。     

活性组分掺杂对低温锰基催化剂脱硝性能的影响

利用Ce和锰盐复配对单组分锰盐活性组分进行掺杂改性,并采用分步共混法制备一系列催化剂。催化剂活性测试显示锰盐复配及Ce的掺杂均能提高锰基催化剂低温活性,且锰盐复配形式的掺杂对催化剂低温活性提高更多。通过对比各催化剂强度状况发现活性组分的掺杂使催化剂的机械强度得到很大提高,而BET结果显示掺杂改性后的锰基催化剂其表面织构得到较大改善。催化剂的XRD结果表明500℃焙烧的锰基催化剂活性组分均以无定形态存在。通过对改性后的催化剂进行NH3-TPD和H2-TPR分析,发现相比于Ce对单组分锰盐的掺杂改性,锰盐复配形式的掺杂改性对催化剂表面酸量和氧化还原性能的提高更加显著。     

NDC-8型脱氢催化剂的工业化运用

本文通过对NDC-6型催化剂及两批NDC-8型催化剂相关运行数据的分析，得出相同工艺条件下，两种催化剂所产烷基苯质量基本相当。NDC-8型催化剂烷基苯产量略高于NDC-6型催化剂，主要副产物重烷苯产量低于NDC-6型催化剂。脱氢反应的选择性和转化率NDC-8型催化剂略好于NDC-6等结论。     

Ni-P非晶态催化剂的制备及应用进展

综述了近些年来Ni-P催化剂的研究成果。分别对Ni-P非晶态催化剂的特点、制备方法,尤其对Ni-P非晶态催化剂的应用方面进行了较为全面的介绍。同时还反映了Ni-P催化剂的最新研究进展,并展望了Ni-P催化剂的研究方向。     

SCR法烟气脱硝催化剂及其应用特性的研究

在介绍SCR法烟气脱硝催化剂工作原理的基础上,着重阐述了3种典型催化剂的技术特点;并分析了影响SCR催化剂性能的一些因素以及应对措施。最后,对SCR催化剂的发展方向以及催化剂国产化提出了一些建议,为火电厂SCR法烟气脱硝系统催化剂的使用提供良好的基础。     

Ultra-thin layer structured anodes for highly durable Iow-Pt direct formic acid fuel cells

Direct formic acid fuel cells （DFAFCs） allow highly efficient low temperature conversion of chemical energy into electricity and are expected to play a vital role in our future sustainable society. However, the massive precious metal usage in current membrane electrode assembly （MEA） technology greatly inhibits their actual applications. Here we demonstrate a new type of anode constructed by confining highly active nanoengineered catalysts into an ultra-thin catalyst layer with thickness around 100 nm. Specifically, an atomic layer of platinum is first deposited onto nanoporous gold （NPG） leaf to achieve high utilization of Pt and easy accessibility of both reactants and electrons to active sites. These NPG-Pt core/shell nanostructures are further decorated by a sub-monolayer of Bi to create highly active reaction sites for formic acid electro-oxidation. Thus obtained layer-structured NPG-Pt-Bi thin films allow a dramatic decrease in Pt usage down to 3 ~tg.cm-2, while maintaining very high electrode activity and power performance at sufficiently low overall precious metal loading. Moreover, these electrode materials show superior durability during half-year test in actual DFAFCs, with remarkable resistance to common impurities in formic acid, which together imply their great potential in applications in actual devices.     

Hydrogen production from formic acid decomposition at room temperature using a Ag-Pd core-shell nanocatalyst

Formic acid (HCOOH) has great potential as an in situ source of hydrogen for fuel cells, because it offers high energy density, is non-toxic and can be safely handled in aqueous solution. So far, there has been a lack of solid catalysts that are sufficiently active and/or selective for hydrogen production from formic acid at room temperature. Here, we report that Ag nanoparticles coated with a thin layer of Pd atoms can significantly enhance the production of H? from formic acid at ambient temperature. Atom probe tomography confirmed that the nanoparticles have a core-shell configuration, with the shell containing between 1 and 10 layers of Pd atoms. The Pd shell contains terrace sites and is electronically promoted by the Ag core, leading to significantly enhanced catalytic properties. Our nanocatalysts could be used in the development of micro polymer electrolyte membrane fuel cells for portable devices and could also be applied in the promotion of other catalytic reactions under mild conditions.     

Controllable self-assembly of Pd nanowire networks as highly active electrocatalysts for direct formic acid fuel cells

Highly dispersed and uniform palladium nanowire networks (NWNs) are synthesized by a controllable, templateless and polyelectrolyte-mediated self-assembly process. In this method, anisotropic Pd(2+)-polysodium-p-styrenesulfonate (PSS) networks are assembled between Pd(2+) ions and SO(3)(-) attached to the pendent aromatic ring of PSS in solution by an electrostatic attraction. Reduction of Pd(II) cations to metallic Pd(0) leads to the formation of Pd nanostructures from cubic nanoparticles to highly dispersed NWNs. The Pd nanostructure formation depends on the rate of nucleation and crystallization of Pd(0) which in turn is controlled by the solution pH and reducing agent. The results demonstrate that highly dispersed and uniform Pd NWNs have a very high aspect ratio and are highly active and stable for the formic acid electrooxidation in acid media, demonstrating the promising potential of Pd NWNs as effective electrocatalysts for direct formic acid fuel cells.     

氢燃料电池用氢气中甲酸的测定——气相色谱法

阐述了采用气相色谱法测定氢燃料电池用氢气中甲酸含量。该方法准确、可靠,便于操作。     

Trimetallic Synergy in Intermetallic PtSnBi Nanoplates Boosts Formic Acid Oxidation

Platinum is the most effective metal for a wide range of catalysis reactions, but it fails in the formic acid electrooxidation test and suffers from severe carbon monoxide poisoning. Developing highly active and stable catalysts that are capable of oxidizing HCOOH directly into CO₂ remains challenging for commercialization of direct liquid fuel cells. A new class of PtSnBi intermetallic nanoplates is synthesized to boost formic acid oxidation, which greatly outperforms binary PtSn and PtBi intermetallic, benefiting from the synergism of chosen three metals. In particular, the best catalyst, atomically ordered Pt₄₅Sn₂₅Bi₃₀ nanoplates, exhibits an ultrahigh mass activity of 4394 mA mg^?1 Pt and preserves 78% of the initial activity after 4000 potential cycles, which make it a state‐of‐the‐art catalyst toward formic acid oxidation. Density functional theory calculations reveal that the electronic and geometric effects in PtSnBi intermetallic nanoplates help suppress CO* formation and optimize dehydrogenation steps.     

Carbon supported polyaniline as anode catalyst: Pathway to platinum-free fuel cells

The effectiveness of carbon supported polyaniline as anode catalyst in a fuel cell (FC) with direct formic acid fuel oxidation is experimentally demonstrated. A prototype FC with such a platinum-free composite anode exhibited a maximum room-temperature specific power of about 5 mW/cm².     

Defect Engineering for Fuel-Cell Electrocatalysts

The commercialization of fuel cells, such as proton exchange membrane fuel cells and direct methanol/formic acid fuel cells, is hampered by their poor stability, high cost, fuel crossover, and the sluggish kinetics of platinum (Pt) and Pt-based electrocatalysts for both the cathodic oxygen reduction reaction (ORR) and the anodic hydrogen oxidation reaction (HOR) or small molecule oxidation reaction (SMOR). Thus far, the exploitation of active and stable electrocatalysts has been the most promising strategy to improve the performance of fuel cells. Accordingly, increasing attention is being devoted to modulating the surface/interface electronic structure of electrocatalysts and optimizing the adsorption energy of intermediate species by defect engineering to enhance their catalytic performance. Defect engineering is introduced in terms of defect definition, classification, characterization, construction, and understanding. Subsequently, the latest advances in defective electrocatalysts for ORR and HOR/SMOR in fuel cells are scientifically and systematically summarized. Furthermore, the structure–activity relationships between defect engineering and electrocatalytic ability are further illustrated by coupling experimental results and theoretical calculations. With a deeper understanding of these complex relationships, the integration of defective electrocatalysts into single fuel-cell systems is also discussed. Finally, the potential challenges and prospects of defective electrocatalysts are further proposed, covering controllable preparation, in situ characterization, and commercial applications.     

Bimetallic Pt–Au thin film electrocatalysts with hierarchical structures for the oxidation of formic acid

A series of bimetallic Pt–Au thin films with different Pt/Au ratios were fabricated on glassy carbon (GC) substrates through galvanic replacement reactions between hierarchical Co thin films prepared by cyclic voltammetric deposition and mixed solutions of HAuCl₄ and H₂PtCl₆. The morphologies of the as-prepared Pt–Au thin films resemble those of the sacrificial Co templates, and the Pt/Au ratios in the films are dependent on the HAuCl₄/H₂PtCl₆ molar ratios in the mixed solutions. Because of good stability and excellent synergistic effect of Au and Pt, the bimetallic films with novel structures display unexpected high catalytic activity for the oxidation of formic acid. The as-prepared hierarchical Pt–Au micro/nanostructures are expected to find applications as catalysts in direct formic acid fuel cells (DFAFCs).     

Formation of porous Pd black induced by in situ catalytic reaction

The in situ heterogeneous catalytic reaction of formic acid decomposition was applied as a 'reaction template' in the synthesis of porous Pd black. The obtained porous Pd black was characterized by transmission electron microscopy, electrochemical measurements and x-ray photoelectron spectroscopy. It was found that the porous Pd black had a high electrochemical active surface area of about 40.2 m2 g(-1) and a clean surface. It could be used directly as a catalyst in many fields such as fuel cells.     

Carbon nanotubes based methanol sensor for fuel cells application

An electrochemical sensor is built using vertically grown multi-walled carbon nanotubes (MWNTs) micro-array to detect methanol concentration in water. This study is done for the potential use of the array as methanol sensor for portable units of direct methanol fuel cells (DMFCs). Platinum (Pt) nanoparticles electro-deposited CNTs (Pt/CNTs) electrode shows high sensitivity in the measurement of methanol concentration in water with cyclic voltammetry (CV) measurement at room temperature. Further investigation has also been undertaken to measure the concentration by changing the amount of the mixture of methanol and formic acid in water. We compared the performance of our micro array sensor built with Pt/CNTs electrodes versus that of Pt wire electrode using CV measurement. We found that our Pt/CNTs array sensor shows high sensitivity and detects methanol concentrations in the range of 0.04 M to 0.10 M. In addition, we found that co-use of formic acid as electrolyte enables us to measure up to 1.0 M methanol concentration.