Catalytic radiant burner for stationary and mobile applications

In present discussions on energy conversion processes aimed at producing both thermal and process heat, catalytic burners provide an alternative approach for future applications. Catalytic burners are advantageous in that they cause only low pollutant emissions during the process of converting chemical energy into heat. In addition, novel engineering concepts require the complete combustion of a variety of fuels and fuel mixtures. Against this background, a novel catalytic radiant burner was developed at the Research Centre Jülich. Under near-stoichiometric conditions, this catalytic burner burns both natural gas with hydrogen admixture in a heat recovery boiler for stationary heat production and methanol with hydrogen admixture in a reformer producing process heat to be used in a fuel cell drive system. The emission data of the catalytic heater were recorded at a nominal power of 11.5 kW, a nominal air/fuel ratio of 1.15 and different hydrogen ratios between 0% and 50% and were 7–3 mg/kW h for carbon monoxide and 3.3–3.9 mg/kW h for nitrogen oxides. The test runs for a catalytic burner to be used for heating a compact reformer in a fuel cell vehicle were carried out at a power density of 15–60 kW/m², a nominal air/fuel ratio of 1.1 and different hydrogen, carbon dioxide and water ratios. For nitrogen oxides emissions of less than 0.4 mg/kW h, the measured carbon monoxide amount ranges between 0 and 13 mg/kW h.     

钙钛矿型La_（1-x）AxCoO_3的制备及其对CH_4燃烧的催化性能

用Na2CO3.10H2O和NaOH混合碱为沉淀剂制得了钙钛矿型结构的La1-XAxCoO3（A：Sr,Ba,Dy,Y;X：0,0.1,0.2）复合氧化物,考察了焙烧温度对催化剂结构和催化活性的影响,发现A位取代后可使催化剂对CH4的催化氧化活性提高;通过与柠檬酸络合法制得的La1-xAxCoO3复合氧化物比较,比较制备方法对催化剂的催化活性也有很大的影响。     

The catalytic heat exchanger using catalytic fin tubes

The characteristics of a catalytic heat exchanger which integrates heat generation and heat exchange into one equipment have been investigated by the experiment and numerical simulation. The surface of the fin tubes was catalyzed by the formation of the oxide layer and the subsequent washcoating of ZrO₂, followed by the impregnation of Pd catalyst. The experimental results showed that the performance of catalytic combustion in the catalytic heat exchanger was more significantly affected by the inlet velocity of the mixture than by its inlet temperature and equivalence ratio. It was also found that the catalytic surface area was a critical parameter to obtain the complete conversion of the mixture. Numerical simulation has been performed with a commercial software FLUENT. The calculated results indicated that the performance of the catalytic combustion was influenced by the catalytic fin configuration as well as the flow pattern of the mixture over the catalytic fins. The results recommend that the number and thickness of catalytic fins should be designed above 6 pieces/inch and less than to achieve the best performance in the catalytic heat exchanger.     

Catalytic combustion assisted methane steam reforming in a catalytic plate reactor

A theoretical study of methane steam reforming coupled with methane catalytic combustion in a catalytic plate reactor (CPR) based on a two-dimensional model is presented. Plates with coated catalyst layers of order of micrometers at distances of order of millimetres offer a high degree of compactness and minimise heat and mass transport resistances. Choosing similar operating conditions in terms of inlet composition and temperature as in industrial reformer allows a direct comparison of CPRs with the latter. It is shown that short distance between heat source and heat sink increases the efficiency of heat exchange. Transverse temperature gradients do not exceed across the wall and across the gas-phase, in contrast to difference in temperature of outside wall and mean gas phase temperature inside the tube usually observed in conventional reformers. The effectiveness factors for the reforming chemical reactions are about one order of magnitude higher than in conventional processes. Minimisation of heat and mass transfer resistances results in reduction of reactor volume and catalyst weight by two orders of magnitude as compared to industrial reformer. Alteration of distance between plates in the range 1- does not result in significant difference in reactor performance, if made at constant inlet flowrates. However, if such modifications are made at constant inlet velocities, conversion and temperature profiles are considerably affected. Similar effects are observed when catalyst layer thicknesses are increased.     

酶的兼职功能和催化混杂性

随着酶学研究的不断深入,最近提出了酶的兼职功能和催化混杂性的新概念.酶的兼职功能和催化混杂性在酶类中广泛存在,Neurospora crassa酪氨酰tRNA合成酶、磷酸葡萄糖异构酶(PGI)、gephyrin和细胞色素C等具有典型的兼职功能;而CAL-B、O-乙酰丝氨酸巯基酶、胰蛋白酶和非血红素二铁酶等表现出很好的催化混杂性.     

Performances of a catalytic foam trap for soot abatement

A catalytic trap for soot particles was prepared by deposition of Cu–V–K–Cl catalyst on a ceramic foam. Catalytic trap performances were evaluated by treating the exhaust of a gas oil burner under different operating conditions. The results obtained showed that ceramic foam is a particularly suitable support for this application since it yields low gas pressure drop, good soot collection efficiency (“deep bed” filtration mechanism), high thermal shock resistance and good contact throughout the filter between soot particles and catalyst surface. In addition, the catalytic foam trap is able to spontaneously regenerate at operating conditions comparable to those typical of diesel engine exhaust and after more than 70 test hours it retains its activity towards soot oxidation.     

Zeolite based films, membranes and membrane reactors: Progress and prospects

The integration of reaction and separation in catalytic membrane reactors has received increasing attention during the past 30 years. The combination promises to deliver more compact and less capital-intensive processes with substantial savings in energy consumption. With the advent of new inorganic materials and processing techniques, there has been renewed interest in exploiting the benefits of membranes in many industrial applications. Zeolite membranes, however, have only recently been considered for catalytic membrane reactor applications. Despite the significant recent interest in these types of membranes there are relatively few reports of the application of such membranes in high-temperature catalytic membrane reactor applications. This can be attributed to a number of limitations that still need to be addressed such as the relatively high price of membrane units, the difficulty of controlling the membrane thickness, permeance, high-temperature sealing, reproducibility and the dilemma of upscaling. A number of research efforts, with some degree of success have been directed to finding solutions to the remaining challenges. This review makes a critical assessment of what has been achieved in the past few years in terms of hurdles that still stand in the way of the successful implementation of zeolite membrane reactors in industry.     

Development of a catalytic combustor with heat exchanger

Catalytic combustion is thought to be a considerable improvement on the traditional one under specific conditions. Due to its special features, catalytic combustion has two strong points compared to flame: no NO_x emission and high reaction efficiency. However, the preheating process of catalytic combustion is an obstacle that deteriorates profitability in operation. So the HTHE (High Temperature Heat Exchanger) is adapted to the system to reinforce the preheating process, and we show that the catalytic combustion is maintained steadily without exceptional heat injection. As a result, the stability on the catalytic surface is the most important operational factor. To achieve it, both mixture gas property and temperature distribution should be controlled.     

FCC柴油氧气氧化萃取法脱硫研究

以氧气作氧化剂,甲酸作催化剂,N-甲基吡咯烷酮(NMP)作萃取剂,采用催化氧化反应与溶剂萃取相结合的方法对催化裂化柴油进行了氧化萃取脱硫实验。通过单因素实验考察了催化剂用量、催化氧化温度、时间、氧气压力及萃取剂的用量等对催化裂化柴油硫质量分数的影响。通过实验得出最适宜的脱硫条件为:反应温度80℃,反应时间90 min,充氧压力0.6 MPa,V(催化剂)∶V(柴油)=10%。经催化氧化,柴油硫质量分数可从1 694.2μg/g降到190.8μg/g,脱硫率达到88.7%;在V(萃取剂)∶V(柴油)=1.0和室温条件下,用NMP萃取3次,柴油硫质量分数为37.5μg/g,小于50μg/g,达到欧Ⅳ排放标准的要求。     

光催化氧化降解处理有机废水研究进展

难降解有机废水治理是环保部门研究的重点课题,文章介绍了光催化氧化的机理及优点,阐述了国内外研究光催化氧化技术处理难降解废水如:表面活性剂废水、焦化废水、农药废水、染料废水、造纸废水及制药废水等的研究进展和一些实用、经济、能用于工业化处理有机废水的光催化氧化技术,展望了光催化氧化技术今后研究的重点方向。     

催化氧化法处理两段炉废水

两段炉废水的处理方法和焦化废水的处理方法基本相同，是采用传统的隔油沉淀、气浮，然后进行生化处理和活性炭深度处理，但活性炭处理投资和运行成本较高，一般企业难以承担，所以不被选用。两段炉废水的处理较合理的方案是：隔油沉淀、气浮、调节池、生化处理、催化氧化法、外排。三相催化氧化法处理焦化废水和两段炉废水是一种新方法，气相是在催化氧化塔内鼓入空气，液相是氧化剂ClO２溶液，固相以活性炭为载体，以金属作为催化剂，这三相在常温常压下氧化有机污染物，将大分子有机污染物氧化分解成小分子有机物或二氧化碳和水，较好地…     

焦化废水深度处理研究进展

焦化废水含有大量有机污染物和有毒无机物,成分复杂,污染物色度高,属较难生化降解的高浓度有机工业废水.经常规方法预处理,再经生化处理后的焦化废水存在氰化物、COD及氨氮等不达标的问题.通过臭氧氧化法、Feton试剂氧化法以及光催化氧化法等高级氧化法,活性炭以及矿物吸附法等三级深度处理可以解决这一问题.介绍了目前焦化废水深度处理的研究进展并进行了展望.     

催化湿式氧化法处理焦化废水的分析

概述了焦化废水水量大、成分复杂、污染物浓度高等水质特点和传统焦化废水处理方法及其缺陷，提出应用催化湿式氧化技术处理焦化废水这一新途径。并就技术和经济方面对催化湿式氧化技术处理焦化废水进行了分析，说明利用该技术处理焦化废水不仅技术上可行而且具有较好的综合效益。指出了催化湿式氧化技术在工业化过程中面临催化剂溶出和反应设备材质要求高等问题。     

光催化降解高浓度COD_(Cr)有机废水处理方法研究

研究了光催化氧化法处理高浓度COD_(Cr)的有机废水。分别研究了H_2O_2的浓度、pH、光照时间和TiO_2的浓度对光催化氧化法对处理高浓度COD_(Cr)的有机废水的处理效率影响,研究结果表明:当H_2O_2浓度为1.5 mmol/L、光照时间30 min和TiO_2浓度5 g/L的条件下,光催化氧化效果达到最好的效果,对松脂废水和印染废水经过TiO_2光催化氧化处理后COD_(Cr)去除率分别为46.7%、69.2%。从两种废水的GC/MS分析结果可知TiO_2光催化氧化法对结构复杂的有机物有较好的降解效果。     

催化氧化法处理印染废水的研究进展

印染废水色度深,毒性大,有机污染物含量高且难降解,采用催化氧化法能将污染物氧化分解。主要介绍了催化氧化法处理印染废水的研究进展,包括光催化氧化法、二氧化氯氧化法、电化学氧化法、Fenton试剂氧化法,对各种方法进行了评价,同时对催化氧化法处理印染废水的发展前景做了简述。     

非均相臭氧催化氧化技术处理有机废水研究进展

有机废水是以有机污染物为主的废水,极易造成水质富营养化,对环境危害大。处理有机废水的方法主要有吸附法、混凝法、芬顿氧化法、膜生物反应法和臭氧氧化法。臭氧催化氧化法主要通过在臭氧氧化体系中加入催化剂,可促进臭氧在水中的自分解,增加水中产生的羟基自由基浓度,从而提高臭氧氧化降解有机物的能力和效率。该方法由于条件可控,成本低廉,处置效率高等优点在有机废水处置领域具有广阔的应用前景。基于此,系统阐述了多种处理有机废水的技术方法以及臭氧催化氧化技术的研究概况,并且着重介绍了非均相臭氧催化氧化催化剂的研究进展。该研究为有机废水的高效处置提供一定的研究基础。     

ClO_2催化氧化处理难降解有机废水的应用研究

简述了二氧化氯(ClO2)的性质与催化氧化原理,介绍了ClO2催化氧化法处理难降解有机废水的工艺条件、处理效果及优点。ClO2催化氧化处理难降解有机废水工艺简单、操作方便,不产生有机卤代烃等二次污染物、氧化能力持久,且在削减COD的同时极大地提高了废水的可生化性,使之能够更好地进行生化处理。     

A^2／O法和催化湿式氧化法处理焦化废水的经济分析

根据焦化废水的水质特点,选择采用A^2／O法和催化湿式氧化法处理焦化废水。通过两种不同工艺处理同源焦化废水的技术比较和经济分析,得出催化湿式氧化法是一种可行的焦化废水处理技术。     

焦化废水催化氧化处理的研究进展

焦化废水是一种氨氮和有机物浓度较高的难生物降解有机废水。笔者详细介绍了国内外近年来焦化废水催化氧化处理的几种方法,并进行了对比;对进一步的研究进行了展望。     

Micro-fiber elements as perfusive catalysts or in catalytic mixers: Flow, mixing and mass transfer

The flow, mixing and mass transfer in a catalytic stirrer containing catalyst coated porous micro-fiber elements, based on a concept introduced by Moulijn, were studied in a lab-scale reactor with 13 samples of materials with fiber diameters from 8 to 35 μm and porosity values between 0.60 and 0.90. Pressure drop in these sintered metallic fiber materials was shown to follow a modified Kozeny–Carman equation:

When rotating in the reactor, the flow through the fiber mats can be estimated from

where α_D is a drag coefficient of around 2.5. Flow through the catalyst in an operational stirrer can be adjusted over several orders of magnitude by manipulating parameters, such as rotational speed, dimension of the fiber stack and its material characteristics.Mass transport between fibers and the liquid flow through fiber stacks follows:

εSh=0.47Re^1/2Sc^1/3