Microporous Materials最新文献_第10页

The effects of lattice composition on the physicochemical properties of H-offretite crystals 晶格组成对氢氟石晶体物理化学性质的影响

Microporous Materials Pub Date : 1997-06-01 DOI: 10.1016/S0927-6513(97)00002-3

M.L. Occelli , H. Eckert , C. Hudalla , A. Auroux , P. Ritz , P.S. Iyer

{"title":"The effects of lattice composition on the physicochemical properties of H-offretite crystals","authors":"M.L. Occelli , H. Eckert , C. Hudalla , A. Auroux , P. Ritz , P.S. Iyer","doi":"10.1016/S0927-6513(97)00002-3","DOIUrl":"10.1016/S0927-6513(97)00002-3","url":null,"abstract":"<div>Several spectroscopic techniques have been used to investigate the acidic properties of a set of galliosilicate molecular sieves with the offretite structure. IR spectra in the OH stretching region contain well-defined bands at or near 3735, 3640, 3600 and 3550 cm−1 that can be attributed to OH groups associated with SiOH, and with M(IV)OH groups located in secondary building units, in the main channels (or in the gmelinite cages), and with M(IV)OH groups associated with oxygens shared by the main channels and the cancrinite cages; M = Al,Ga. Spectra of chemisorbed pyridine show that all crystals contain both Bronstedt (B) and Lewis (L) acid sites, and that the presence of Ga seems to decrease B-acid strength and to increase the L-sites' density and strength. Microcalorimetry experiments with ammonia and pyridine as probe molecules show that Ga insertion into the aluminosilicate framework increases the strength of the strongest acid sites and that the presence of Ga generate a heterogeneous distribution of acid site strengths absent in the parent Al-analogs. Moreover, in H,Ga-offretites, there is a drastic reduction in acid site density while the initial acid site strength remains high. NMR results suggest that the observed effects can be attributed, in part, to the presence of extra-framework Al and Ga atoms. Levels of Al(VI) and Ga(VI), as well as partial lattice degradation, strongly depend on the NH4-exchange and calcination procedure used to activate these offretite crystals.</div>","PeriodicalId":100926,"journal":{"name":"Microporous Materials","volume":"10 1","pages":"Pages 123-135"},"PeriodicalIF":0.0,"publicationDate":"1997-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0927-6513(97)00002-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80644088","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

The difference in adsorption capacity between Fe-PILCs and modified Fe-BuA- and Fe-Zr-PILCs Fe-PILCs与改性Fe-BuA-和Fe-Zr-PILCs吸附性能的差异

Microporous Materials Pub Date : 1997-06-01 DOI: 10.1016/S0927-6513(96)00122-8

I. Heylen, E.F. Vansant

{"title":"The difference in adsorption capacity between Fe-PILCs and modified Fe-BuA- and Fe-Zr-PILCs","authors":"I. Heylen, E.F. Vansant","doi":"10.1016/S0927-6513(96)00122-8","DOIUrl":"10.1016/S0927-6513(96)00122-8","url":null,"abstract":"<div>Iron(III) oxide pillared clays have low micropore volumes (0.04 cm3 g−1) and surface areas (95 m2 g−1). In order to increase the porosity and thereby the adsorption capacity, two different modification procedures were carried out. The first modification is based on the preadsorption of butylammonium ions between the clay sheets prior to the pillaring procedure with the iron precursors. This gives rise to a decrease of the Fe pillar density which results in an increased porosity (Fe-BuA-PILC). Preadsorption of butylammonium ions doubles the adsorption capacity of an Fe-PILC. A second modification is the incorporation of Zr into the Fe precursors to create mixed Fe-Zr pillars with entirely new properties (pillar charge, pillar symmetry, etc.) creating a pillared clay with a different enhanced porosity. These pillared clays were tested with respect to their adsorption and desorption capacities towards CCl4, CHCl3, CH2Cl2 and CH4 at 0 °C. These experiments indicate that the adsorption capacity of the mixed Fe-Zr-PILC is four times higher than pure Fe-PILC. Not only does the capacity differ, but the isotherm type also changes, indicating that adsorbents with different properties can be created by means of simple modification techniques.</div>","PeriodicalId":100926,"journal":{"name":"Microporous Materials","volume":"10 1","pages":"Pages 41-50"},"PeriodicalIF":0.0,"publicationDate":"1997-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0927-6513(96)00122-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90084908","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: 16

Effect of the particle size for photocatalytic decomposition of water on Ni-loaded K4Nb6O17 负载ni的K4Nb6O17光催化分解水的粒径影响

Microporous Materials Pub Date : 1997-05-01 DOI: 10.1016/S0927-6513(96)00112-5

Shigeru Ikeda , Akira Tanaka , Kiyoaki Shinohara , Michikazu Hara , Junko N. Kondo , Ken-ichi Maruya , Kazunari Domen

引用次数: 68

The effect of ageing on the microwave synthesis of zeolite NaA 老化对微波合成NaA沸石的影响

Microporous Materials Pub Date : 1997-05-01 DOI: 10.1016/S0927-6513(96)00119-8

P.M. Slangen, J.C. Jansen, H. van Bekkum

引用次数: 99

Synthesis of zeolites in the system Na2O-SiO2-Al2O3-H2O-glycerol na20 - sio2 - al2o3 - h2o -甘油体系中沸石的合成

Microporous Materials Pub Date : 1997-05-01 DOI: 10.1016/S0927-6513(96)00120-4

Sanyuan Yang, A.G. Vlessidis, N.P. Evmiridis

{"title":"Synthesis of zeolites in the system Na2O-SiO2-Al2O3-H2O-glycerol","authors":"Sanyuan Yang, A.G. Vlessidis, N.P. Evmiridis","doi":"10.1016/S0927-6513(96)00120-4","DOIUrl":"10.1016/S0927-6513(96)00120-4","url":null,"abstract":"<div>The synthesis of zeolites from a mixture of a non-aqueous glycerol aluminosilicate gel and a controlled quantity of water has been studied. It was found that a minimum water content in the synthesis mixture is required to achieve a measurable crystallization rate. A further increase of the water content may facilitate the crystallization process of omega and then switch the crystal structure of the product from omega to analcime. At the Si/Al ratio of 6.95 in the synthesis mixture an increase of the NaOH content leads to a product sequence of amorphous → omega → analcime → analcime and sodalite. An increase of the Si/Al ratio in the synthesis mixture leads to a product sequence of sodalite → omega(+analcime) → ferrierite → magadiite. At the Si/Al ratio of 6.95 in the synthesis mixture a change of the alkali cations in a sequence of Li+ +Na+ → K+ + Na+→ Rb+ +Na+ → Cs+ + Na+ corresponds to a product sequence of omega (+ analcime) → offretite → offretite → analcime. With the new synthesis system, crystalline microporous materials including omega, offretite, analcime, and ferrierite can be readily obtained. The behaviors of the new synthesis system are discussed and compared with those of the normal hydrothermal synthesis system for zeolites.</div>","PeriodicalId":100926,"journal":{"name":"Microporous Materials","volume":"9 5","pages":"Pages 273-286"},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0927-6513(96)00120-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76186725","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: 14

Sorbate-induced changes in the 29Si MAS NMR spectrum of highly siliceous MCM-22 山梨酸诱导的高硅MCM-22的29Si MAS NMR谱变化

Microporous Materials Pub Date : 1997-05-01 DOI: 10.1016/S0927-6513(96)00069-7

Gordon J. Kennedy, Stephen L. Lawton

引用次数: 4

The homogeneous nature of clear TPA-silicalite-1 precursor solutions 透明tpa -硅石-1前驱体溶液的均匀性

Microporous Materials Pub Date : 1997-05-01 DOI: 10.1016/S0927-6513(96)00116-2

Brian J. Schoeman

引用次数: 31

Dry synthesis of B-MFI, MTN- and MTW-type materials B-MFI, MTN-和mtw型材料的干法合成

Microporous Materials Pub Date : 1997-05-01 DOI: 10.1016/S0927-6513(96)00118-6

U. Deforth , K.K. Unger , F. Schüth

引用次数: 26

IR and TPD (temperature-programmed desorption) studies of carbon dioxide on basic site active for 1-butene isomerization on alkali-added zeolite X 加碱沸石X上1-丁烯异构化反应中二氧化碳碱性位的IR和TPD研究

Microporous Materials Pub Date : 1997-05-01 DOI: 10.1016/S0927-6513(96)00114-9

Fuyuki Yagi, Hideto Tsuji, Hideshi Hattori

引用次数: 41

Acidity modification during the agglomeration of ZSM-5 with montmorillonite 蒙脱土对ZSM-5团聚过程的酸性改性

Microporous Materials Pub Date : 1997-05-01 DOI: 10.1016/S0927-6513(96)00110-1

M.D. Romero , J.A. Calles , A. Rodríguez , A. de Lucas

引用次数: 13