催化剂及助剂颗粒强度测定方法

化学工程中的催化剂性能测试方法催化剂是化学工程中非常重要的组成部分，它们能够在反应中起到促进或者限制反应速率的作用。

为了确定催化剂的性能，科学家们开发了许多测试方法。

本文将探讨几种常见的催化剂性能测试方法。

一、比表面积比表面积是催化剂性能的重要参数之一。

催化剂的比表面积越大，其活性通常也会更高。

一种常见的测定比表面积的方法是吸附法，其中氮气吸附法是最常用的。

氮气吸附法利用氮气分子在催化剂表面的吸附行为来测定催化剂的比表面积。

二、形貌表征催化剂的形貌也对其性能有着重要影响。

常见的形貌表征方法包括电子显微镜（SEM）和透射电子显微镜（TEM），它们可以提供催化剂微观结构的信息，如颗粒大小、形状等。

此外，扫描电镜（SEM）联合能谱仪（EDS）还可以用来分析催化剂元素的分布。

三、X射线衍射（XRD）X射线衍射是一种常用于催化剂研究的技术。

通过照射催化剂样品，X射线衍射可以提供催化剂的晶体结构、物相和亚晶等信息。

催化剂的晶相信息对了解催化性能和稳定性有重要影响。

四、表面酸碱性催化剂的表面酸碱性质对其催化性能也有很大影响。

常用的测试方法包括吸附露点测定（TPD）和NH3程序升温脱附（NH3-TPD）等。

这些方法可以确定催化剂表面酸碱位点的数量和强度，从而评估催化剂的酸碱性。

五、催化性能测试反应最直接的方式来评估催化剂性能就是进行催化反应测试。

例如，在催化裂化反应中，可以通过测定产品分布和转化率来评估催化剂的性能。

此外，通过构建微观动力学模型，可以更加深入地了解催化剂的反应机理和性能。

综上所述，化学工程中的催化剂性能测试方法主要包括比表面积测定、形貌表征、X射线衍射、表面酸碱性测试和催化性能测试反应等。

这些方法在催化剂研究和应用中发挥着重要作用，能够帮助科学家们更好地理解催化剂的特性和性能，以及优化催化反应的条件和过程。

催化剂是一种能够促进化学反应速率的物质，它可以通过提高反应物分子间的碰撞频率或降低反应物分子在碰撞时所需的能量来加速化学反应的进行。

在许多工业生产过程中，催化剂都起到了至关重要的作用。

对催化剂的性能进行准确的表征和测试显得尤为重要。

催化剂的性能与其粒径和表观堆密度密切相关。

粒径大小直接影响着催化剂的比表面积和活性中心的分布，而表观堆密度则影响着催化剂在反应器中的填充效果和传质性能。

开发出准确可靠的测试手段来对催化剂的粒径和表观堆密度进行表征至关重要。

本文将从催化剂粒径和表观堆密度测试手段的基本原理、常用方法以及应用前景三个方面进行探讨。

一、催化剂粒径测试手段催化剂的粒径是指催化剂颗粒的直径大小，它直接影响着催化剂的比表面积和活性中心的分布。

目前常用的催化剂粒径测试手段主要包括：1. 毛细管法：毛细管法是一种通过对催化剂样品进行液相浸渍，然后利用毛细管测定浸渍液的毛细管压力来计算出颗粒的粒径大小的方法。

该方法操作简便，但对催化剂的形状要求较高，且对颗粒的分布范围有限。

2. 氮气吸附法：氮气吸附法是一种通过将催化剂样品暴露在氮气环境下，利用BET等温线测定吸附量从而推算出比表面积和粒径大小的方法。

该方法适用范围广，适用于大部分形态的催化剂粒子。

3. 激光粒度分析法：激光粒度分析法是一种通过激光衍射原理来测定催化剂颗粒大小和分布范围的方法。

该方法测量精度高，适用于各类形态的催化剂颗粒。

以上三种方法各有其优缺点，在实际应用中需要根据催化剂的具体形态和实验要求选择合适的测试手段进行粒径分析。

二、催化剂表观堆密度测试手段催化剂的表观堆密度是指催化剂颗粒在一定条件下的堆积重量与体积之比，它与催化剂在反应器中的填充效果和传质性能有着密切的关系。

目前常用的催化剂表观堆密度测试手段主要包括：1. 振实密度法：振实密度法是一种通过将催化剂样品放入密闭容器中，施加振实力使催化剂颗粒自由落体振实，从而测定振实后的重量与容器体积之比来计算出催化剂的表观堆密度的方法。

催化剂的颗粒分析与机械强度的测定摘要：介绍了催化剂的颗粒分析与机械强度的测定方法及理论。

关键词：催化剂；颗粒分析；机械强度；测定工业催化剂或载体，是具有发达孔系的颗粒集合体，一般情况是一定的原子（分子）或离子按照晶体结构规则组成含微孔的纳米（nm ）级晶粒（原级粒子）；因制备化学条件和化学组成不同，若干晶粒聚集为大小不一的微米级颗粒（part-icle ），即二次粒子；通过成型工艺制备，若干颗粒又可堆积成球、条、锭片、微球粉体等不同几何外形的颗粒集合体，即粒团（pellet ），尺寸则随需要由几十微米到几毫米，特别情况者可达百毫米以上。

近年迅速开发的纳米材料，是二次粒子纳米化或不存在二次粒子的颗粒集合体实际成型催化剂的粒团与颗粒等效球半径比大于102，颗粒或二次粒子间堆积形成的介（或大）孔孔隙与晶粒内和晶粒间微孔构成该粒团的孔系结构（见图1）；晶粒和颗粒间连接方式、接触点键合力以及接触配位数则决定了粒团的抗破碎和磨损性能。

由于催化剂的催化活性中心大多位于微孔的内表面，介（或大）孔主要贡献于反应物流的传递，而表征传递阻力对反应速率影响的有效因子是Thiele 模数和微孔扩散系数与介（或大）孔扩散系数比的函数[1]，Thiele 模数Φ反映催化剂颗粒密度、比表面积、成型粒团尺寸与传质扩散关系[2-4]，2/1)/(sg p D Ak S R ρφ=……………………………（1） 式（1）中p ρ为颗粒密度（即汞置换法密度，定义为单粒催化剂质量与其几何体积比）；g S 为比表面积；R 为催化剂粒团的等效球半径；D s 为球形催化剂粒团（颗粒）的总有效扩散系数；k 为催化剂内表面反应速率。

所以，在化学组成与结构确定的情况下，催化剂的催化性能与运转周期决定于构成催化剂的颗粒-孔系宏观物性，因此对其进行研究表征和测定对于开发催化剂的意义是显见的[5]。

图1 催化剂颗粒集合体示意图1 催化剂的颗粒分析1.1 颗粒尺寸颗粒尺寸（particle size）称为颗粒度，实际催化剂颗粒是成型的粒团即颗粒集合体，因此狭义催化剂颗粒度系指成型粒团的尺寸；负载型催化剂负载的金属或其化合物粒子是晶粒或二次粒子，它们的尺寸符合颗粒度的正常定义。

催化剂性能的评价、测试和表征 概述主要内容• 活性评价和动力学研究• 催化剂的宏观物理性质测定 • 催化剂微观性质的测定和表征工业催化剂性能评价的目的①为应用提供依据②为开发制备提供判别的标准 ③基础研究的需要 评价内容① 使用性能活性，选择性，寿命 ②.宏观性能：比表面积，孔结构，形状与尺寸 ③.微观性能：晶相组成，表面酸碱性• 工业催化剂的性能要求及其物理化学性质4催化剂测试• 催化剂的物理性质的测定 ，包括宏观物理性质（孔容、孔径分布、比表面等）及微观物理性质（催化剂的晶相、晶格缺陷、微观粒径尺寸等） 几个基本概念评价（evaluation ），对催化剂的化学性质考察和定量描述； 测试（test ），对工业催化剂物理性质（宏观和微观）的测定； 表征（Characterization ），综合考察催化剂的物理、化学的性质和内在联系，特别是研究活性、选择性、稳定性的本质原因。

第一节．活性评价和动力学研究活性测定方法：流动法和静态法，流动法用得最多（一般流动法、流动循环法、催化色谱法） 本质上是对工业催化过程的模拟流动循环法、催化色谱法多用于反应动力学和反应机理 活性测试的目的a ）由催化剂制造商或用户进行的常规质量控制检验b ）快速筛选大量催化剂，以便为特定的反应确定一个催化剂评价的优劣。

c ）更详尽的比较几种催化剂d ）测定在特定催化剂上反应的详尽动力学，包括失活或再生动力学。

e ）模拟工业反应条件下催化剂的连续长期运转 活性的表示方法• 转化率(X A)活性的表示方法• 选择性(S)%100⨯=的起始摩尔数反应物已转化的摩尔数反应物A A X A %100⨯=摩尔数已转化的某一反应物的所得目的产物的摩尔数S收率(Y)Y=X A ×S• 时空得率（STY ）：每小时、每升催化剂所得产物的量关于时空得率：指在一定条件（温度、压力、进料空速）下，单位体积或单位质量催化剂所得到产物量，多用于工业生产和工业设计，可直接计算出量产。

催化剂测定与表征技术催化剂在化学工业中扮演着重要的角色，它们能够加速反应速度，提高产物选择性，降低反应温度等。

为了充分了解催化剂的性能和稳定性，科学家们发展了各种测定和表征催化剂的技术。

本文将介绍几种常用的催化剂测定与表征技术。

一、物理吸附法物理吸附法是一种常用的催化剂表征技术。

通过测定催化剂表面吸附气体的物理吸附量，可以确定催化剂的比表面积、孔径分布和孔容等参数。

常用的物理吸附法包括比表面积测定、孔径分布测定和吸附等温线测定等。

其中，比表面积测定常用的仪器是比表面仪，可以测定催化剂的比表面积；孔径分布测定则可以通过气孔大小对吸附剂进行分类；吸附等温线测定可以获得催化剂的孔容和孔径分布。

二、扫描电子显微镜（SEM）扫描电子显微镜是一种高分辨率表征催化剂表面形貌和微观结构的技术。

通过扫描电子显微镜，可以观察到催化剂表面的形貌、颗粒大小和分布等信息。

同时，通过能谱分析功能，还可以确定催化剂表面元素的组成和分布。

扫描电子显微镜的应用广泛，可以对不同种类的催化剂进行表征，为改进催化剂性能提供依据。

三、透射电子显微镜（TEM）透射电子显微镜是一种高分辨率表征催化剂内部结构的技术。

通过透射电子显微镜，可以观察到催化剂微观结构的细节，如晶体结构、晶胞参数、晶界和缺陷等。

透射电子显微镜还可以进行能谱分析，确定催化剂微观结构元素的组成和分布。

透射电子显微镜在催化剂研究中起到了至关重要的作用，对于揭示催化机理和改善催化剂性能具有重要意义。

四、X射线衍射（XRD）X射线衍射是一种广泛应用于催化剂表征的技术。

通过X射线衍射，可以确定催化剂晶体结构、晶胞参数和晶面取向等信息。

X射线衍射还可以进行定性和定量分析，确定催化剂中晶体的相对含量。

X射线衍射技术是研究催化剂晶体结构和相变行为的重要手段，为催化剂的合成和改良提供了重要信息。

五、傅里叶变换红外光谱（FTIR）傅里叶变换红外光谱是一种用于催化剂表征的非常有用的技术。

通过傅里叶变换红外光谱，可以确定催化剂表面的吸附物质、化学键特征和表面活性位点等信息。

Designation:D4179−11Standard Test Method forSingle Pellet Crush Strength of Formed Catalysts and Catalyst Carriers1This standard is issued under thefixed designation D4179;the number immediately following the designation indicates the year of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon(´)indicates an editorial change since the last revision or reapproval.1.Scope1.1This test method covers determining the resistance of formed catalysts and catalyst carriers to compressive force and is applicable to regular catalyst shapes such as tablets and spheres.Extrudates,granular materials,and other irregular shapes are specifically excluded.1.2This test method determines the average crush strength in the range from0to50lbf(0to220N).Some materials may have crush strengths above50lbf(220N);the test method is applicable to these materials,but the precision of the test is not known.1.3The values stated in inch-pound units are to be regarded as standard.The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.4This standard does not purport to address all of the safety concerns,if any,associated with its use.It is the responsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1ASTM Standards:2E177Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE456Terminology Relating to Quality and StatisticsE691Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method3.Terminology3.1Definitions of Terms Specific to This Standard:3.1.1pellets—any catalyst shape—tablets,spheres,or other similar configuration—that is not otherwise excluded from the scope of this test method.3.1.2tablets—tableted cylindrical catalyst particles,either solid or hollow core,with lengths that do not vary from the mean by more than610%.4.Summary of Test Method4.1Individual pellets taken from a representative sample are placed between twoflat surfaces,subjected to a compressive load,and the force required to crush the pellet is measured.The procedure is replicated and the average of all measurements taken is determined.5.Significance and Use5.1This test method is intended to provide information concerning the ability of a catalyst shape to retain physical integrity during use.6.Apparatus6.1A suitable compression testing device is required,con-sisting of the following:6.1.1Calibrated Gauge,marked for direct reading of the force in pounds(newtons).Additionally,a suitable system (mechanical,hydraulic,or pneumatic)must be provided so that the rate of force application is both uniform and controllable within specified limits.6.1.2Tool Steel Anvils,between which the sample will be crushed.The faces of the tool steel anvils shall be smooth and free from recesses or ridges that would interfere with uniform contact along the major axis of the pellet.When testing tablets or spheres,the anvils may be of any convenient size or shape1This test method is under the jurisdiction of ASTM Committee D32onCatalysts and is the direct responsibility of Subcommittee D32.02on Physical-Mechanical Properties.Current edition approved Oct.1,2011.Published November2011.Originallyapproved st previous edition approved in2006as D4179–01(2006).DOI:10.1520/D4179-11.2For referenced ASTM standards,visit the ASTM website,,orcontact ASTM Customer Service at service@.For Annual Book of ASTMStandards volume information,refer to the standard’s Document Summary page onthe ASTM website.Copyright©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959.United Statesas long as their length and width are greater than the corre-sponding dimensions of the tablet or pellet being tested (see Fig.1).7.Sampling7.1A test sample of 50to 200individual pieces shall be obtained from larger composites by riffling or splitting in accordance with STP 447A,3(paragraph 5.12)with the aim of obtaining a representative sample that represents shape and size distribution of the larger composite.The size of the sample shall depend on the precision required and the homogeneity of the material being tested.7.2Pretreat the test sample(s)at 400615°C for not less than 3h.Normally,this treatment can take place in air;however,in the case of materials that might react with air at elevated temperatures (such as prereduced catalysts)the heat treatment should take place in an inert atmosphere.Care should be taken to ensure that the pretreatment does not alter the inherent strength or structure of the sample as evidenced by changes in surface area or phase.Any modifications to pre-treatment conditions should be noted in the report.7.3After heating,cool the test sample(s)in a desiccator or other suitable container to eliminate the possibility of moisture adsorption prior to testing.N OTE 1—Since many catalyst formulations are strong adsorbents,the use of 4A indicating (cobalt-treated)molecular sieves as a desiccating medium is suggested.Regenerate the desiccant at 220to 260°C,as required.8.Calibration and Standardization8.1Prior to use,set the test apparatus to zero and calibratewith any commercially available force gauge with marked graduations of no more than 1⁄2lbf (2N)and having accuracytraceable to the National Institute of Standards and Technology,or other similar authority.9.Procedure9.1Remove from the desiccator only that number of pellets that can be tested within a 10-min period.(Warning—Ensure that moisture pick-up in the 10-min period will not signifi-cantly affect the pellet crush strength.)9.2Place a single catalyst pellet between the anvils of the compression testing device.Orient each pellet in the same direction before crushing.For those pellets capable of being tested in different orientations,report the one used.Fig.1shows pellets in radial and axial e tweezers,forceps,or other suitable device or procedure to prevent the transfer of moisture from the operator’s hands to the piece being tested.9.3Apply increasing force at a uniform rate in the range of 1to 10lbf/s (4.4to 44N/s)until the pellet crushes or pression of surface irregularities or limited fracturing of a pellet followed by continued resistance to increasing load are not to be used as criteria for determining the endpoint of this test.9.4Read and record,to the nearest one-half graduation,the force indicated on the calibrated dial of the apparatus at the instant of collapse.9.5Separate the anvils and remove all residue with a soft cloth or brush.Ensure that the faces of the anvils are free from adhering particles.9.6Repeat steps 9.2through 9.5until all pellets in the sample have been crushed.Record the crush strength for each pellet tested.10.Calculation10.1Calculate the average crush strength (X¯),retaining one more decimal place than the recorded values,as follows:X¯lbf ~N !5~(X !/~n !(1)where:^X =the sum of all observed crush strengths and n =the number of pellets crushed.10.2Calculate the standard deviation of the n readings to three significant digits as follows:S 5Œ(~X 2X¯!2n 21lbf ~N !(2)where:S =standard deviation of the individual strengthvalues and^(X −X¯)2=sum of the squares of the deviations of each recorded reading from the average strength.N OTE 2—Many calculators are programmed to perform these operations and to report average and standard deviation directly.It is important to verify that the program chosen uses the n −1denominator rather than n in calculating standard deviation.3STP 447A,Manual on Test Sieving Methods ,ASTM International,West Conshohocken,PA19428.FIG.1Radial and AxialCrush11.Report11.1Report the average crush strength to one more decimal place than the recorded data on the individual strengths.For pellets capable of being tested in different orientations,the one used should be reported.11.2Report the 80%spread (that is,the range within which 80%of the individual pellet strengths are expected to fall,assuming that individual pellets form a normal distribution).Calculate as follows:80%spread 5X¯61.28S (3)11.3Report the 95%reliability of the average reported in11.1.This is the uncertainty inherent in the reported average,expressed as the range within which 95%of the averages of an infinite number of test samples of n pellets would be expected to fall were they to be similarly drawn from the same lot and tested.Calculate as follows:95%reliability 5X¯61.96S /=n (4)11.4Report the applied rate of force increase,if available.12.Precision and Bias 412.1Test Program—An interlaboratory study was con-ducted in which the named property was measured in twoseparate test materials in six separate laboratories.Practice E691,modified for nonuniform data sets,was followed for the data reduction.Analysis details are in the research report.12.2Precision—Pairs of test results obtained by a procedure similar to that described in the study are expected to differ in absolute value by less than 2.772S ,where 2.772S is the 95%probability interval limit on the difference between two test results,and S is the appropriate estimate of standard deviation.Definitions and usage are given in Terminology E456and Practice E177,respectively.Test Result (Consensus Mean)lbf 95%Repeatability Inter-val (Within Laboratory)lbf (%of mean)95%Reproducibility Inter-val (Between Laboratories)lbf (%of mean)20.19(Spheres) 1.22(6.03) 1.76(8.74)16.50(Tablets)1.00(6.03)2.77(16.8)12.3Bias—This test method is without known bias.13.Keywords13.1catalyst;crush strength;single pelletASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this ers of this standard are expressly advised that determination of the validity of any such patent rights,and the risk of infringement of 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