Overview of Precious Metal Content Analysis Methods in Automotive Catalytic Converter

With the increasing awareness of environmental protection, people’s concern of pollution issues arising. Vehicles, as the most important means of transportation, its exhaust emission has received considerable attention. The catalytic converter is able to purify harmful substances in exhaust gas. The absolute content of precious metals in the catalytic converter dominates the exhaust gas purification effect. Accurate detection of precious metal content is of great significance for controlling the cost of catalysts, ensuring catalytic performance and recovering precious metals from spent catalysts. We herein summarized several instruments for precious metals content exploration, such as X-ray fluorescence spectrometer (XRF), atomic absorption spectrometer (AAS), inductively coupled plasma emission spectrometer (ICP) and spectrophotometer. In this thesis, the feasibility of using various devices for characterizing precious metal content in catalytic converters is analyzed and their strengths or weaknesses are elaborated.

Four-channel catalytic micro-reactor based on alumina hollow fiber membrane for efficient catalytic oxidation of CO

The traditional automotive catalytic converter using commercial ceramic honeycomb carriers has many problems such as high back pressure,low engine efficiency,and high usage of precious metals.This study proposes a four-channel catalytic micro-reactor based on alumina hollow fiber membrane,which uses phase inversion method for structural molding and regulation.Due to the advantages of its carrier,it can achieve lower ignition temperature under low noble metal loading.With Pd/CeO_(2) at a loading rate of 2.3%(mass),the result showed that the reaction ignition temperature is even less than 160℃,which is more than 90℃ lower than the data of commercial ceramic substrates under similar catalyst loading and airspeed conditions.The technology in turn significantly reduces the energy consumption of the reaction.And stability tests were conducted under constant conditions for 1000 h,which proved that this catalytic converter has high catalytic efficiency and stability,providing prospects for the design of innovative catalytic converters in the future.

Numerical Simulation of Cold-Start Emission for the Three-Way Catalytic Converter: Mathematical Model and Result Analysis

This paper integrated a two-dimensional axisymmetrical transient model applicable to cold-start emission applications. The model can be used to simulate and explain effects of the flow and temperature distribution on performance of a converter. The evolutions of distribution of the temperature and concentration in the monolith during the cold-start period and the effects of flow distribution in the monolith on the cold-start performance are simulated in terms of the integrated model. The investigation indicates that the axial and radial gradients of temperature of the solid become steeper as the inlet gas temperature ramp increases; this furthermore results in the movement of reaction region in the monolith, and the flow distribution in the monolith affects the radial distribution of temperature of the solid;the radial gradients of temperature of the solid become greater as the flow uniformity index decreases, whereas the light-off time doesn't always increase as the flow uniformity index decreases. The analyses on the distribution of temperature and concentration in the monolith show that the catalytic reaction zone concentrates in central area near the front face. The predicted curves of the velocity distribution have a good agreement with the experimental data.

Study on Influence of Gasoline Sulfur Content on Performance of Vehicle Exhaust Catalytic Converter

This paper has investigated the influence of gasoline sulfur content on durability of catalytic converter for vehicle exhaust gas. Two gasoline samples with different sulfur contents (equating to 150 μg/g and 50 μg/g of sulfur, respectively) were used to examine the durability and performance of catalytic converter on the bench test. The test results have revealed that in comparison to the influence of sulfur on ageing of catalytic converter the thermal ageing had a more remarkable impact on the performance of catalytic converter, and the performance of catalytic converter could be restored by high-temperature desulfurization process after ageing by the high-sulfur gasoline sample (containing 150 μg/g of sulfur) .

NUMERICAL SIMULATION OF EFFECTS OF WALL THICKNESS AND CELL DENSITY ON THE THREE-WAY CATALYTIC CONVERTER PERFORMANCE

The transient symmetric mathematical model is established, and the effects of the wall thickness and cell density on the performance of a three-way catalytic converter are studied using numerical modeling. The conclusions show that the light-off time and the pressure drop through a converter are decreased, and the conversion efficiency during the warm-up period keeps almost invariant with reduction of the wall thickness of substrates, and that the pressure drop through a converter and a conversion efficiency during the warm-up state increases, and the light-off time almost keeps invariant when increasing cell density of substrates. Therefore, future catalytic converters should develop in the direction of thin wall thickness and high cell density substrates simultaneously.

Sulfur poisoning mechanism of three way catalytic converter and its grey relational analysis

Combining a detailed catalytic surface reaction mechanism with noble metal and promoter elementary reactions, a new three-way catalytic converter(TWC) reaction mechanism is established. Based on the new mechanism, steady condition numerical simulation is carried out, and the change of light-off temperatures and conversion efficiency with various SO2 contents is obtained. By grey relational analysis(GRA), the relational grade between conversion efficiency and SO2 content is obtained. And, the result shows that SO2 content has the most important influence on C3H6 and NOX conversion efficiency. This provides an important reference to the improvement of activity design of TWC, and may provide guidance for the condition design and optimization of TWC.

Comparison of Properties of Tumor Necrosis Factor-α Converting Enzyme (TACE) and Some Matrix Metalloproteases (MMPs) in Catalytic Domains

The crystal structural data of TACE, MMP-1, MMP-2, MMP-3 and MMP-9 were obtained from PDB database, and then their catalytic domains＇ properties including conformation, molecular surface hydrophobicity and electrostatic potential were analyzed and compared by using Insight II molecular modeling software. It was found that the conformation and molecular surface hydrophobicity of catalytic domains of TACE and MMPs were not obviously different, but the molecular surface electrostatic potential of catalytic domain of TACE＇ and MMPs had obvious differences. The findings are helpful in the Rational Drug Design of TACE selective inhibitor.

Converter塔底油裂化助剂在催化裂化装置上的应用

在催化裂化装置中加入能够增加重油裂化能力、提高平衡催化剂活性的Converter塔底油裂化助剂(简称Converter助剂)。工业应用表明,使用Converter助剂后,在原料性质变差的情况下,干气质量分数下降0.10个百分点,焦炭质量分数没有变化,油浆质量分数下降1.08个百分点,总液收率提高1.08个百分点;汽油研究法辛烷值保持在92左右,烯烃体积分数不大于35%;催化剂单耗下降0.011 kg/t。

Combined Effect of a Catalytic Reduction Device with Waste Frying Oil-Based Biodiesel on NOx Emissions of Diesel Engines

Internal combustion engines with application in automobiles and other relevant industries constitute significant environmental pollution via the release of toxic exhaust gasses like carbon monoxide (CO), hydrocarbons (HC), particulate matter (PM), and nitrogen oxide (NOx). Engine researchers and manufacturers are challenged to develop external and internal measures to ensure environmentally friendly solutions to accommodate and conform to the growing list of emission standards. Therefore, this work presents an experimental investigation of the NOx emission profile of a diesel engine that is fuelled and fitted with waste frying oil-based biodiesel and catalytic converter. Using a single-cylinder, four-stroke air-cooled CI engine at a constant speed of 1900 rpm and different loadings of 25%, 50%, 75%, and 100%;fitted with a catalytic converter at the exhaust outlet of the engine and linked to a dynamometer and a gas analyser, an experiment was conducted at biodiesel/diesel volume blends of B0 (0/10), B5 (5/95), B20 (20/80), B30 (30/70), B70 (70/30), B100 (100/0);and 30% concentration (v/v), 0.5 litre/hr flow rate of aqueous urea from the catalytic converter. The results show an increasing NOx emission as the biodiesel component increased in the blend. The catalytic converter showed a downward NOx reduction with a significant 68% reduction in efficiency at high exhaust gas temperatures. It is concluded that the combined utilisation of waste frying oil-based biodiesel and the catalytic converter yields substantial NOx emission reduction.

废汽车尾气催化剂特性解析及其对稀贵金属回收的影响

废汽车尾气催化剂是重要的稀贵金属二次资源,随着未来报废汽车的逐渐增加,废汽车尾气催化剂的数量相应增加。当前从废汽车尾气催化剂中回收稀贵金属(铂族金属、稀土金属和稀有金属等)的方法较多,但由于对废汽车尾气催化剂的特性了解不够全面,大多数回收方法在回收率、环境友好性、经济性上都不够理想,亟需对废汽车尾气催化剂进行科学全面地了解。对废汽车尾气催化剂的基本特征、物相及成分组成、废汽车尾气催化剂中PGMs、Ree、Zr等稀贵金属元素的赋存形式、元素迁移及分布状态、熔化过程等进行研究,全面了解废汽车尾气催化剂;揭示了催化剂中铂族金属被部分氧化、活性组分发生渗透转移、有价元素的非均匀分布、催化剂涂层烧损开裂、杂质元素的污染等因素共同造成了催化剂失效退役的失活机理;采用火法熔炼,合理设计选择熔炼渣剂及捕集剂回收其中的稀贵金属,可以有效地避免废催化剂自身特性所带来稀贵金属回收率低效的问题。

汽油机冷机间歇性抖动问题的研究

汽油机冷起动后,催化器需快速达到较高温度,才能具有一定的转化效率。此阶段的控制策略往往是通过提高转速、减小点火提前角、加浓混合气等手段使排气温度迅速升高,但会影响到NVH性能和驾驶性。针对某汽油机催化器加热阶段严重的抖动问题,首先通过对源头和传递路径进行分析和排查,确认起燃阶段燃烧稳定性差是引起抖动的根本原因;然后对相关硬件进行排查,对多组控制参数下的座椅振动、燃烧稳定性进行扫描试验以及对排放进行摸底试验,寻求出一套排放和NVH性能均达标的控制参数;最后通过调整挡位转速控制策略,解决起步阶段突兀的驾驶性问题,使该汽油车型冷机怠速工况各性能指标均达标。

Vapour Treatment Method Against Other Pyro-and Hydrometallurgical Processes Applied to Recover Platinum From Used Auto Catalytic Converters

Today more and more cars are produced every year. All of them have to be equipped with catalytic converters, the main role of which is to obtain substances harmless to the environment instead of exhausted gases. Catalytic converters contain platinum group metals （PGM） especially platinum, palladium and rhodium. The price of these metals and their increasing demand are the reasons why today it is necessary to recycle used auto catalytic converters. There are many available methods of recovering PGM metals from them, especially platinum. These methods used mainly hydrometallurgical processes; however pyrometallurgical ones become more and more popular. The article presents results of the research mainly concerning pyrometallurgical processes. Two groups of research were carried out. In the first one different metals such as lead, magnesium and copper were used as a metal collector. During the tests, platinum went to those metals forming an alloy. In other research metal vapours were blown through catalytic converter carrier （grinded or whole）. In the tests metals such as calcium, magnesium, cadmium and zinc were applied. As a result white or grey powder （metal plus platinum） was obtained. The tables present results of the research. Processing parameters and conclusions are also shown. To compare efficiency of pyrometallurgical and hydrometallurgical methods catalytic converter carrier and samples of copper with platinum obtained from pyrometallurgical method were solved in aqua regia, mixture of aqua regia and fluoric acid.

Novel Electrically Stimulated Catalytic Converter Prototype for Replacement of Conventional Auto Exhaust Emission Converters

High voltage electrostatics and corona discharge are utilized for various applications in pollution and environmental control. The traditional applications have many flaws due to improper construction of electrode design and assembly that cause system failure, in particular when electrically stimulated devices are exposed to high humidity. A new innovative-patented design by Hamade, electrically stimulated catalytic converter(ESCC),eliminates such flaws and shows the wide practical applications of the new design. The new design utilized previous patented designs and work of the same inventor but retrofitted for catalytic auto exhaust emission control. The current and previous patents include: employing electrically stimulated filtration(ESF) to replace high efficiency particulate air(HEPA) filters, treatment of biological and infectious diseases, electret fabrication, and, most notably, the invention of a new electrically stimulated catalytic converter(ESCC). The electrically stimulated catalytic converter invention includes an exhaust conduit fed from the engine exhaust port with a housed corona charger apparatus. The opposite end is opened to the atmosphere outside of the vehicle or connected to a reduced-size catalytic converter. The corona charger is intrusively or non-intrusively associated with a main flow path defined by the exhaust conduit. The corona charger includes at least one electrode, which may be recessed away from, the main flow path. A plurality of corona chargers may be used in various combinations, optimally a two dimensional grid. The electrically stimulated catalytic converter is adapted to treat and eliminate auto exhaust pollution emission to air.

Auto catalytic converters growing in China

The air pollution caused by au-to emission becomes more and moreserious in China, which arouses Chinese Government to attach great attention to controlling auto tail gas pollution as a very important task. In Beijing, the municipal govern-ment has taken the lead in imple-menting the emission standard e-quivalent to European No. Ⅰ stan-

基于工程伦理视角的汽车产品创新方法

工程伦理是基于工程学科和非工程学科不断融合发展起来的交叉学科,对于创新活动强调“负责任创新”的基本理念,为产品创新提供了一个有利的视角。本文从工程伦理倡导运用系统性思想实施“负责任创新”的理念出发,分析并提出基于系统性思想的汽车产品创新方法,即系统性视角转换分析法,并以汽车用三元催化转换器为产品实例进行了分析,表明该方法能够有效引导设计人员针对产品的每个要素进行创新机会的探寻,启发设计人员从产品设计所涉及的各种层面和角度去发现以前不曾注意到的创新机遇,进而促使设计人员通过系统性的思考和判断获取多个创新方案。

国六轻型车催化转化器应用现状的分析

采集2019年至2021年共计917辆申报轻型车第6阶段排放标准的新车催化转化器数据,分别从载体单元数量分布、封装形式、三元催化器(TWC)和颗粒捕集器(GPF)分布、催化剂涂层厂分布、贵金属含量及贵金属测试结果合格率进行统计分析。结果表明:采集数据车辆多选用两个催化转化器载体单元,且多为TWC+GPF前后分布模式,除了TWC含有贵金属,95%的GPF也含有贵金属;贵金属多选用二贵金属元素,其中钯(Pd)、铑(Rh)配方占比最多,单贵金属元素和三贵金属元素配方占比较少;贵金属含量分布范围大,GPF贵金属含量普遍低于TWC贵金属含量;催化剂涂层多选用进口涂层厂及少部分国内涂层厂,且贵金属测试结果合格率高,部分国内涂层厂贵金属含量测试结果合格率低。因此可结合排放数据综合分析原因,实现对车用尾气排放控制系统的有效监控,从源头预防角度为大气污染提供防治思路。

水热老化对三元催化器理化特性影响的试验研究

为探究水热老化条件对车用发动机三元催化器(three-way catalytic converter,TWC)理化性质的影响规律,利用快速水热老化试验装置对TWC样品进行了不同温度和不同空速的水热老化处理,并对老化前后的样品进行了N2物理吸附、X射线衍射(X-ray diffraction,XRD)、X射线光电子能谱(X-ray photoelectron spectroscopy,XPS)、透射电子显微镜(transmission electron microscopy,TEM)等微观表征测试分析。试验结果表明:相同老化时间下,随着温度升高,TWC的比表面积急剧减小,孔容降低,孔径增大,CeO_(2)粒径增大,催化器载体的孔道物理结构表现出一定程度的坍塌;提高老化温度,Ce^(3+)相对含量有所降低,储氧能力等化学性质变化明显。相比温度,空速变化对TWC的物理结构影响较小,提高空速,Ce^(3+)相对含量升高,储氧能力增强。在水热老化过程中,温度是TWC性能劣化和失活的主要因素。

国四100 mL踏板摩托车三效催化器贵金属减量化研究

三效催化器是控制摩托车尾气排放最有效的技术手段。而当前三效催化器中起主要作用的活性组分贵金属的价格持续升高,对行业下游特别是主机厂带来巨大的成本压力。优化催化器系统设计,减少贵金属用量是降低三效催化器成本的关键。基于一款100 mL排量国四踏板摩托车,在该车原催化器技术方案基础上,通过对催化器的系统设计,从贵金属配比、催化剂涂层配方和催化器载体结构选型等方面开展优化降本研究。实验结果表明通过优化方案可使得贵金属用量下降69%,同时催化剂新鲜态和耐久后排放性能满足国四排放要求且均优于原方案。

汽油机实验间DOC尾气二次净化性能分析

当汽油机排放的尾气中氧气浓度过低时,经催化器处理后的尾气仍有大量一氧化碳(CO)和碳氢化合物(HC)残余排出,从而对大气造成污染,因此在催化前需要及时调整氧气浓度。同时汽油机在试验间进行试验时,由于工况比较恶劣,导致整车的催化器失效,从而造成尾气浓度超标,因此需要对发动机尾气进行二次净化。通过设计一种在线式氧传感器以及电动补气阀,可在氧浓度不足时及时补充所需氧气,使空燃比达到三元催化转化器的有效工作区间。同时在后段增加了氧化型催化反应器,在三元催化器失效时,对尾气中的有害成分:HC和CO进行二次处理,从而降低尾气排放超标的风险。