BS 4359-4-1995 Determination of the specific surface area of powders - Recommendations for methods of determination of metal surface area using gas adsorption techniques《粉末表面系数的测定 .pdf
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1、BRITISH STANDARD BS 4359-4: 1995 Determination of the specific surface area of powders Part 4: Recommendations for methods of determination of metal surface area using gas adsorption techniquesBS4359-4:1995 This British Standard, having been prepared under the directionof the Materials and Chemicals
2、 Sector Board (I/-), waspublished under the authorityof the Standards Boardand comes into effect on 15 April 1995 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference LBI/37 Draft for comment 94/500726 DC ISBN 0 580 23926 8 Committees responsible for this
3、 British Standard The preparation of this British Standard was entrusted by the Materials and Chemicals Sector Board to Technical Committee LBI/37, upon which the following bodies were represented: BLWA Ltd. (the Association of the Laboratory Supply Industry) British Cement Association British Coal
4、Corporation Coated Abrasives Manufacturers Association Guild of Metal Perforators Institution of Chemical Engineers Institution of Mining and Metallurgy Ministry of Defence NABIM Society of Chemical Industry Society of Cosmetic Scientists Woven Wire Association The following bodies were also represe
5、nted in the drafting of the standard, through a subcommittee: Aluminium Federation China Clay Association Defence Research Agency GAMBICA (BEAMA Ltd.) Loughborough University of Technology Royal Pharmaceutical Society of Great Britain Royal Society of Chemistry University of Bradford Amendments issu
6、ed since publication Amd. No. Date CommentsBS4359-4:1995 BSI 08-1999 i Contents Page Committees responsible Inside front cover Foreword ii Introduction 1 1 Scope 1 2 References 1 3 Definitions 1 4 Principles 2 5 Sample preparation 3 6 Volumetric method 5 7 Flow methods 12 8 Calculation of the metal
7、surface area 14 9 Reporting of results 15 Annex A (informative) Modification of method for other metals 16 Figure 1 Typical apparatus for the volumetric method 6 Figure 2 Typical adsorption isotherm for hydrogen on platinum (linear scales) 10 Figure 3 Typical linearized plot of adsorption against pr
8、essure (linear scales) 10 Figure 4 Typical apparatus for the flow methods 11 Figure 5 Schematic TCD response in pulsed flow 12 Figure 6 Schematic TCD response in continuous flow 12 Table 1 Stoichiometry values recommended for use in calculations 14 Table 2 Values for surface density of metal atoms r
9、ecommended for use in calculations 15 List of references Inside back coverBS4359-4:1995 ii BSI 08-1999 Foreword This Part of BS 4359 has been prepared by Technical Committee LBI/37. Other Parts of the standard are: Part 1: Recommendations for gas absorption (BET) methods; Part 2: Recommended air per
10、meability methods; Part 3: (withdrawn) Calculation from the particle size distribution. This Part of BS 4359 describes recommended methods for the determination of metal surface area using gas adsorption techniques only and should not be used or quoted as a specification. References to this standard
11、 should indicate that the methods used are in accordance with BS 4359-4:1995. This British Standard calls for the use of substances and/or procedures that may be injurious to health if adequate precautions are not taken. It refers only to technical suitability and does not absolve the user from lega
12、l obligations relating to health and safety at any stage. In particular, attention is drawn to the Health and Safety Executive Control of Substances Hazardous to Health (COSHH) Regulations (1988) 1. A British Standard does not purport to include all the necessary provisions of a contract. Users of B
13、ritish Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 16, an inside back cover and a back c
14、over. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS4359-4:1995 BSI 08-1999 1 Introduction Metal catalysts are used extensively in manufacturing processes in for example, the fin
15、e chemicals, petrochemical and food industries. These catalysts may be of the supported or Raney type (see3.8). A non-manufacturing use is that of environmental emission control. Supported catalysts comprise metal particles located on a support surface. Specific examples include nickel on alumina (h
16、ydrogenation), platinum on alumina (reforming) and palladium on carbon (for fine chemicals and hydrogenation). Supported metal catalysts are used in many different physical forms depending on how the reaction is to be conducted, for instance powders, granules, extrudates or monoliths. Metal catalyst
17、s function by providing specific sites for adsorption of reactant molecules on to the surface of metal atoms. Bonds in the reactant become weakened and reaction is facilitated. Desorption of the products from the catalyst leaves the sites available for further reaction. In straightforward cases, and
18、 in the absence of mass transport control, a supported metal catalysts activity is often proportional to the metal area. However the activity per unit metal area is not always independent of metal particle size. Laboratory methods for evaluating the metal area of supported metal catalysts include ga
19、s adsorption techniques to assess the amount of metal surface that is accessible to the adsorptive molecule. The adsorptive used depends on the nature and application of the catalyst being evaluated. As with other forms of gas adsorption analysis, static volumetric and flow methods can be used for t
20、he evaluation. 1 Scope This Part of BS 4359 describes recommended methods for the determination of metal surface area using gas adsorption. They are suitable for supported monometallic catalysts where the metal surface area differs from the total surface area. These methods may also be suitable for
21、other metal catalysts, such as some Raney materials. Specific recommendations are given for the determination of metal surface area of nickel, palladium, platinum and copper. Information on the extension of these methods to other metals in Groups VIII and IB of the periodic table is given in Annex A
22、. Recommendations are made regarding the most suitable gas and test methods for a given metal/support combination. Both chemisorption methods and those which employ surface reaction (or titration) are described. Volumetric or flow techniques may be used to determine the amount of gas chemisorbed. Re
23、commendations are given to correct for any reversible adsorption detected using the volumetric technique. 2 References 2.1 Normative references This Part of BS 4359 incorporates, by dated or undated reference, provisions from other publications. These normative references are made at the appropriate
24、 places in the text and the cited publications are listed on the inside back cover. For dated references, only the edition cited applies; any subsequent amendments to or revisions of the cited publication apply to this Part of BS 4359 only when incorporated in the reference by amendment or revision.
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