Microporous Materials最新文献

Non-silica periodic mesostructured materials: recent progress 非二氧化硅周期性介结构材料:最新进展

Microporous Materials Pub Date : 1997-12-01 DOI: 10.1016/S0927-6513(97)00059-X

Abdelhamid Sayari, Ping Liu

引用次数: 184

The use of linear azo compounds as probes for the characterization of micropores of molecular sieves 利用线性偶氮化合物作为表征分子筛微孔的探针

Microporous Materials Pub Date : 1997-12-01 DOI: 10.1016/S0927-6513(97)00063-1

L.-T. Yuen, J.S. Geilfuss, S.I. Zones

{"title":"The use of linear azo compounds as probes for the characterization of micropores of molecular sieves","authors":"L.-T. Yuen, J.S. Geilfuss, S.I. Zones","doi":"10.1016/S0927-6513(97)00063-1","DOIUrl":"10.1016/S0927-6513(97)00063-1","url":null,"abstract":"<div><p>A new method for determining the pore sizes of zeolites is introduced. Data are obtained spectrophotometrically for the uptake, from an isooctane solution, of alkane diazodicarboxylate chromophores. The size of the alkane groups was varied, thereby introducing differences in the sizes of the probe molecules being adsorbed. The method demonstrates no uptake of chromophore for small pore zeolites, somewhat hindered uptake for intermediate pore zeolites, and variable uptake rates for large-pore zeolites because the solvent can compete. Crystallite size, pore system dimensionality, and hydrophobicity (in the case of the large pore zeolites) are shown to affect the uptake data. Determination of products residing in the pores after 1000 min of solution circulating over the zeolite bed was determined by TGA/MS analysis. The method was applied to several high silica zeolites with known structures, as well as to unknown structures like SSZ-25 and 35. The study confirmed that the unusual zeolite SSZ-25 has pore openings larger than silicalite or ZSM-5 but smaller than a number of so-called large pore zeolites. Limitations, and future prospects for the use of this relatively simple system, are discussed.</p></div>","PeriodicalId":100926,"journal":{"name":"Microporous Materials","volume":"12 4","pages":"Pages 229-249"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0927-6513(97)00063-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87610232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Temperature programmed desorption of normal alkanes from silicalite-1 硅石-1中正构烷烃的程序升温解吸

Microporous Materials Pub Date : 1997-12-01 DOI: 10.1016/S0927-6513(97)00068-0

Yiwen Yang, Lovat V.C. Rees

引用次数: 12

Influence of dealumination on the micropore adsorption in FCC catalysts 脱铝对FCC催化剂微孔吸附的影响

Microporous Materials Pub Date : 1997-12-01 DOI: 10.1016/S0927-6513(97)00073-4

Gabriela de la Puente, Ulises A. Sedran

{"title":"Influence of dealumination on the micropore adsorption in FCC catalysts","authors":"Gabriela de la Puente, Ulises A. Sedran","doi":"10.1016/S0927-6513(97)00073-4","DOIUrl":"10.1016/S0927-6513(97)00073-4","url":null,"abstract":"<div><p>The adsorption of nitrogen and argon on laboratory steam dealuminated and equilibrium commercial FCC catalysts (Y zeolite plus matrix) of various types, covering a wide range of catalyst properties, was studied. Different approaches were used to estimate micropore volumes. Micropore size distributions were assessed based on the area-averaged cylindrical micropore model. With both nitrogen and argon adsorption isotherms, it was possible to locate the peak indicating the pore size in the fresh catalysts at the expected value of 0.74 nm if proper values for the physical parameters in the model were adopted. On the dealuminated samples, nitrogen and argon yielded significantly different results. Ar-based micropore size distributions suggested that the physical parameters involved in the model change with the variations in the chemical composition accompanying dealumination. N<sub>2</sub>-based pore size distributions are more sensitive to variations in the overall adsorption energy due to the growing influence of specific contributions (quadrupolar interactions). The magnitude of the minimum of potential energy in the nitrogen adsorption process decreases with dealumination up to a stable value for Si/Al ratios over about 8.</p></div>","PeriodicalId":100926,"journal":{"name":"Microporous Materials","volume":"12 4","pages":"Pages 251-260"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0927-6513(97)00073-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81116598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Invariability of the particulate properties during the thermal treatment of potassium-exchanged zeolite A: evidence for “amorphous crystals” 钾交换沸石A热处理过程中颗粒性质的不变性:“非晶”的证据

Microporous Materials Pub Date : 1997-12-01 DOI: 10.1016/S0927-6513(97)00074-6

C. Kosanović, B. Subotić

引用次数: 17

Clustering of cobalt in CoAPO-5 molecular sieves CoAPO-5分子筛中钴的聚类

Microporous Materials Pub Date : 1997-12-01 DOI: 10.1016/S0927-6513(97)00078-3

H.F.W.J. van Breukelen , G.J.C. Kraaijveld , L.J.M. van de Ven , J.W. de Haan , J.H.C. van Hooff

引用次数: 12

Dealumination of small- and large-port mordenites: A comparative study 小孔和大孔丝光沸石脱铝的比较研究

Microporous Materials Pub Date : 1997-12-01 DOI: 10.1016/S0927-6513(97)00067-9

S. Moreno , G. Poncelet

{"title":"Dealumination of small- and large-port mordenites: A comparative study","authors":"S. Moreno , G. Poncelet","doi":"10.1016/S0927-6513(97)00067-9","DOIUrl":"10.1016/S0927-6513(97)00067-9","url":null,"abstract":"<div><p>Large-port (LP) and small-port (SP) mordenites with different particle size and shape have been submitted under similar conditions to known dealumination procedures in view of comparing their respective behavior, and establishing the similarities and discrepancies among the dealuminated solids. The dealuminated zeolites have been characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), acidity measurements with ammonia and X-ray photoelectron spectroscopy (XPS). The particle size of the starting mordenite markedly influenced the extraction of Al when dealumination was performed by direct acid attack or dry thermal treatment. Admission of steam during calcination noticeably improved the removal of Al from SP mordenite compared with other methods. Elimination of the extra-framework Al species produced at the calcination step required acid concentration as high as 6 M. (Hydro)thermally dealuminated LP mordenites exhibited similar surface and bulk chemical composition. Conversely, dealuminated SP mordenites showed surface enrichment in Al up to Si/Al ratios of about 40, and depletion in Al at higher ratios. These surface/bulk heterogeneous distributions were suppressed when dealumination combined preliminary acid leaching and steaming. Dealuminated small- and large-port mordenites exhibited differences in their textural characteristics, and for both, a contraction of the unit cell volume and the development of meso- and secondary microporosity.</p></div>","PeriodicalId":100926,"journal":{"name":"Microporous Materials","volume":"12 4","pages":"Pages 197-222"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0927-6513(97)00067-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85135194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 50

Investigation of organosilanes as structure-directing agents in zeolite synthesis 有机硅烷作为分子筛合成结构导向剂的研究

Microporous Materials Pub Date : 1997-12-01 DOI: 10.1016/S0927-6513(97)00084-9

Larry W. Beck , Ping Lu , William P. Weber , Mark E. Davis

引用次数: 10

Vibrational spectra of completely siliceous zeolite A 全硅质沸石A的振动谱

Microporous Materials Pub Date : 1997-12-01 DOI: 10.1016/S0927-6513(97)00082-5

Yining Huang, Zhimei Jiang

引用次数: 36

The multiple equilibrium model for characterizing porous materials 表征多孔材料的多重平衡模型

Microporous Materials Pub Date : 1997-12-01 DOI: 10.1016/S0927-6513(97)00035-7

Wm. Scott Kassel, R.S. Drago

{"title":"The multiple equilibrium model for characterizing porous materials","authors":"Wm. Scott Kassel, R.S. Drago","doi":"10.1016/S0927-6513(97)00035-7","DOIUrl":"10.1016/S0927-6513(97)00035-7","url":null,"abstract":"<div><p>In this work, a multiple-process equilibrium model was used to analyze gas-solid adsorption equilibria in the porous carbonaceous material, BPL. Methane was used as a non-polar gaseous probe molecule to study the adsorption process. This analysis provided adsorption capacities, <em>n<sub>i</sub></em>, along with the associated equilibrium constants, <em>K<sub>i</sub></em>, for the three processes needed to fit the isotherms. The temperature dependence of the <em>K<sub>i</sub></em> allowed determination of the enthalpies of the adsorption processes, Δ<em>H<sub>i</sub></em>. These enthalpies were greater than the heat of vaporization for methane but less than that usually associated with chemisorption processes. Simulated adsorption data were generated based on the methane analysis to determine the effect of pore size distribution on the analysis. It is concluded that, given a continuous distribution of pore sizes, a large number of adsorption processes is necessary to describe accurately the total adsorption. For heterogeneous distributions, as is observed in activated carbon materials, it is possible to resolve discontinuities in the distribution.</p></div>","PeriodicalId":100926,"journal":{"name":"Microporous Materials","volume":"12 4","pages":"Pages 189-195"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0927-6513(97)00035-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89828555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2