Mesoporous silica-aluminas as catalysts for the alkylation of aromatic hydrocarbons with olefins

Perego, Carlo; Amarilli, Stefano; Carati, Angela; Flego, C.; Pazzuconi, G.; Rizzo, Caterina; Bellussi, Giuseppe

doi:10.1016/s1387-1811(98)00267-4

Cited by 105 publications

(58 citation statements)

References 30 publications

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“…Increased attention towards alumina-silica was recognized once more upon preparation of an active mesoporous structure [8]. While alkylation of aromatic hydrocarbons by olefins was convincingly reported [9], Corma et al [10], Calemma et al [11] and Peratello et al [12] found that MSA (mesoporous alumina-silica) catalysts are highly suitable acidic components for the preparation of supported metal bi-functional catalysts applied in hydroisomerization, hydrocracking and olefins oligomerization. Among the reported MSA mesoporous syntheses by sol-gel and reaction conditions controlling parameters such as pore size, structure, distribution, hydrothermal stability and the density of acid sites [13,14] various templates and pore regulating agents such as tetra alkyl ammonium cation and tetra alkyl ammonium hydroxide [15][16][17] were reported as effective for such tasks.…”

Section: Introductionmentioning

confidence: 99%

Optimization of silica content in alumina-silica nanocomposites to achieve high catalytic dehydrogenation activity of supported Pt catalyst

Saber

Gobara

2014

Egyptian Journal of Petroleum

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The present work aims at obtaining a suitable and selective catalyst for catalytic dehydrogenation reactions through designing pore structures of silica-containing alumina nanocomposites by optimizing silica content in the structure. In this trend, series of silica-containing alumina nanocomposites with different molar ratios Al 2 O 3 /SiO 2 were prepared by the solvothermal method. According to surface characterization of silica-containing alumina nanocomposites, the sample with the highest molar ratio of Al 2 O 3 /SiO 2 (2.06) showed mesoporous structure with selective pore sizes of 3.7 and 4.6 nm. In addition, it had a high surface area value of 308 m 2 /g. Furthermore, SEM and TEM images of the same sample showed ultra fine sized particles in the nano size (7-17 nm). Dehydrogenation catalysts, as developed structures, were then achieved by loading 0.6 wt.% platinum metal over the prepared nanocomposites. Performances of the prepared nanocatalysts were investigated via the dehydrogenation of a model compound namely; cyclohexane. Experimental results showed that the Pt catalyst supported on the silica-containing alumina nanocomposites with the highest molar ratio of Al 2 O 3 /SiO 2 , is an efficient and selective catalyst toward the dehydrogenation reaction. This was revealed in terms of 100% selectivity of this catalyst toward the conversion of cyclohexane at all ranges of temperatures with the conversion reaction being temperature dependent. Practically, the total conversion of cyclohexane increased with increasing reaction temperature and reached 100% at 450°C while the prepared catalyst demonstrated absolute selectivity. ª 2014 Production and hosting by Elsevier B.V. on behalf of Egyptian Petroleum Research Institute.

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Section: Introductionmentioning

confidence: 99%

Optimization of silica content in alumina-silica nanocomposites to achieve high catalytic dehydrogenation activity of supported Pt catalyst

Saber

Gobara

2014

Egyptian Journal of Petroleum

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“…ZnPC-2 consists of trimeric zinc-phosphonocarboxylate clusters (Zn 3 - 2 , Zn 3 -SBU) and pbdc linkers (Figure 1a). The three Zn II ions in the Zn 3 -SBU form an isoscelestriangle with Zn(1)···Zn (1) i (i: x, 1/2Ày, 1/4Àz) and Zn(1)/ Zn (1) i ···Zn(2) distances of 4.61 and 3.56 , respectively. The oxygen atoms from the phosphonate of pbdc tridentately capture the isoscelestriangle.…”

Section: Resultsmentioning

confidence: 99%

“…[1][2][3] The paraoriented dialkylated aromatics, such as para-diisopropylbenzene, para-ethyltoluene, para-diethylbenzene, para-cymenes and 4-tert-butyltoluene, are very important chemical materials. The Friedel-Crafts reaction is a typical catalytic alkylation reaction and generally results the mixture of para-, meta-and ortho-oriented products.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Isoreticular Zinc(II)‐Phosphonocarboxylate Frameworks and Their Application in the Friedel–Crafts Benzylation Reaction

Deng¹,

Ling²,

Xia³

et al. 2011

Chemistry A European J

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Three isoreticular zinc(II)-phosphonocarboxylate frameworks, namely {[Zn(3)(pbdc)(2)]·2H(3)O}(n) (ZnPC-2), {[Zn(3)(pbdc)(2)]·Hpd·H(3)O·4H(2)O}(n) (Hpd@ZnPC-2) and {[Co(1.5)Zn(1.5)(pbdc)(2)]·2H(3)O}(n) (CoZnPC-2) (H(4)pbdc=5-phosphonobenzene-1,3-dicarboxylic acid, pd=pyrrolidine), were solvothermally synthesized. ZnPC-2 has a 3D structure based on trinuclear Zn(II) clusters (Zn(3)-SBU) showing 3D interconnected channels. Hpd@ZnPC-2 contains an isoreticular framework of ZnPC-2 with small channels blocked by Hpd molecules. In CoZnPC-2, Zn(II) ions in ZnPC-2 are partially substituted by Co(II) ions. The Friedel-Crafts benzylation reactions were carried out over these isoreticular porous materials. The catalytic results reveal that ZnPC-2 is an excellent heterogeneous Lewis acid catalyst with a high selectivity (>90%) towards less bulky para-oriented products. The catalytic reaction has been proved to occur inside the pore of ZnPC-2, and the immobilized Zn(3)-SBUs are the active sites.

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“…Tendo em vista que a eficiência e a aplicabilidade de um catalisador estão diretamente relacionadas com a acessibilidade aos sítios ativos e esta depende da natureza da estrutura porosa e das características de inchamento dessa estrutura, procurou-se otimizar a acessibilidade, produzindo copolímeros meso-e macroporosos com área específica e porosidade elevadas [16][17][18][19][20][21][22][23] . Verificou-se que teores de n-heptano mais elevados na composição da mistura diluente provocaram um significativo aumento da área específica e do volume de poros, sendo este aumento mais pronunciado sob menores graus de diluição.…”

Section: Conclusõesunclassified

Suportes poliméricos para catalisadores sulfônicos: síntese e caracterização

2004

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Resumo: Suportes poliméricos foram sintetizados por meio da copolimerização de estireno (S) e divinilbenzeno (DVB) em suspensão aquosa na presença de misturas diluentes constituídas por tolueno e n-heptano, solventes esses considerados como bom e mau para o polímero respectivamente, em composições variadas. Foram usados dois teores de DVB (60 e 80%) e dois graus de diluição (100 e 200%). Os suportes foram caracterizados no estado seco e no estado inchado e suas propriedades foram relacionadas com os parâmetros de síntese. No estado seco, os copolímeros foram analisados quanto à densidade aparente, à área específica, ao volume de poros e à morfologia. No estado inchado foi observado o comportamento dos copolímeros em tolueno e em n-heptano. Neste trabalho são comentadas as vantagens do uso desses suportes para a preparação de catalisadores sulfônicos e se faz uma comparação entre esses catalisadores e os catalisadores homogê-neos convencionais comumente usados em sínteses orgânicas. Palavras-chave: Copolímeros de estireno-divinilbenzeno, suportes poliméricos, morfologia, caracterização, catalisadores sulfônicos imobilizados. Polymer Supports for Sulfonic Catalysts: Synthesis and CharacterizationAbstract: Polymer supports were synthesized by aqueous suspension copolymerization of styrene and divinylbenzene in the presence of diluent mixtures formed by toluene (good solvent) and heptane (bad solvent) in different compositions. Two relative concentrations of DVB (60 and 80%) and two dilution degrees relative to the monomers volume (100 and 200%) were used in the copolymerizations. The supports were characterized in dry and swollen states and their properties were related to the synthesis parameters. In the dry state, the bulk density, surface area, pore volume and morphology of the copolymers were determined. In the swollen state, a study was made of the copolymers behavior in toluene and heptane respectively. In this work the advantages of using polymer supports in the preparation of sulfonic catalysts were discussed including a comparison between homogeneous and heterogeneous catalysts often used in organic synthesis.

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Mesoporous silica-aluminas as catalysts for the alkylation of aromatic hydrocarbons with olefins

Cited by 105 publications

References 30 publications

Optimization of silica content in alumina-silica nanocomposites to achieve high catalytic dehydrogenation activity of supported Pt catalyst

Optimization of silica content in alumina-silica nanocomposites to achieve high catalytic dehydrogenation activity of supported Pt catalyst

Synthesis of Isoreticular Zinc(II)‐Phosphonocarboxylate Frameworks and Their Application in the Friedel–Crafts Benzylation Reaction

Suportes poliméricos para catalisadores sulfônicos: síntese e caracterização

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