From designer Lewis acid to designer Br&amp;oslash;nsted acid towards more reactive and selective acid catalysis

Yamamoto, Hisashi

doi:10.2183/pjab.84.134

Cited by 32 publications

(7 citation statements)

References 51 publications

(38 reference statements)

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“…. ) has been reported producing Lewis sites with the concomitant reduction in the amount of Brönsted sites [58,59]. To support the inter-cationic exchange between Cu 2+ and/or Zn 2+ and protons in CZA-xHPW/Ti hybrids, they are characterized by DRIFTS (Figure 11) because the structural modes of the KU, between 1150 and 700 cm −1 , are sensitive to changes in its composition [35].…”

Section: Structure and Acidity Of Cza-xhpw/ti Bifunctional Hybrid Catalystsmentioning

confidence: 98%

Direct Synthesis of Dimethyl Ether from Syngas on Bifunctional Hybrid Catalysts Based on Supported H3PW12O40 and Cu-ZnO(Al): Effect of Heteropolyacid Loading on Hybrid Structure and Catalytic Activity

et al. 2020

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The performance of bifunctional hybrid catalysts based on phosphotungstic acid (H3PW12O40, HPW) supported on TiO2 combined with Cu-ZnO(Al) catalyst in the direct synthesis of dimethyl ether (DME) from syngas has been investigated. We studied the effect of the HPW loading on TiO2 (from 1.4 to 2.7 monolayers) on the dispersion and acid characteristics of the HPW clusters. When the concentration of the heteropoliacid is slightly higher than the monolayer (1.4 monolayers) the acidity of the clusters is perturbed by the surface of titania, while for concentration higher than 1.7 monolayers results in the formation of three-dimensional HPW nanocrystals with acidity similar to the bulk heteropolyacid. Physical hybridization of supported heteropolyacids with the Cu-ZnO(Al) catalyst modifies both the acid characteristics of the supported heteropolyacids and the copper surface area of the Cu-ZnO(Al) catalyst. Hybridization gives rise to a decrease in the copper surface area and the disappearance of the strong acidic sites typical of HPW nanocrystals, showing all hybrids similar acid sites of weak or medium strength. The activity of the hybrids was tested for direct DME synthesis from syngas at 30 bar and 250 °C; only the hybrids with HPW loading higher than 1.4 monolayers showed activity for the direct synthesis of DME, showing that the sample loaded with 2.7 monolayers of heteropolyacid had higher activity than the reference hybrid representative of the most widely applied catalysts based on the combination of Cu-ZnO(Al) with HZSM-5. In spite of the high activity of the hybrids, they show a moderate loss in the DME production with TOS that denotes some kind of deactivation of the acidity function under reaction conditions.

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Section: Structure and Acidity Of Cza-xhpw/ti Bifunctional Hybrid Catalystsmentioning

confidence: 98%

Direct Synthesis of Dimethyl Ether from Syngas on Bifunctional Hybrid Catalysts Based on Supported H3PW12O40 and Cu-ZnO(Al): Effect of Heteropolyacid Loading on Hybrid Structure and Catalytic Activity

et al. 2020

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“…Magnotta and Gates [20] reported that the acidic property of the complex formed by AlCl 3 -sulfonic acid can be similar to that of the superacid solution of SbF 5 + FSO 3 H. Shi et al [23] showed that the efficiency of acid-catalyzed transesterification and esterification reactions depend on the subtle balance between Lewis and Brønsted acidities. It has been proved that the coordination of a Lewis acid with a Brønsted acid can increase its original acidity [24]. Therefore, the design of dual acid catalysts based on resins can be advantageous in the BPA production.…”

Section: Introductionmentioning

confidence: 99%

ZnCl2-modified ion exchange resin as an efficient catalyst for the bisphenol-A production

Wang

Dong

Chen

et al. 2014

Chinese Chemical Letters

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“…Heteropolyacids (HPAs) with Keggin structure are friendly acid catalysts for various organic reactions 1 2 3 4 . In this context, Lewis acidic HPAs have been synthesized through partial exchange of protons with metal cations 5 6 7 . Sn-exchanged Sn 0.75 H 0.25 PW 12 O 40 has been studied in different reactions including the selective hydrolysis of cellulose to glucose 8 9 , cyanosilylation of ketones and aldehydes 10 , esterification or transesterification 11 12 , and Friedel-Crafts alkylation reactions 13 .…”

mentioning

confidence: 99%

Tailoring the Synergistic Bronsted-Lewis acidic effects in Heteropolyacid catalysts: Applied in Esterification and Transesterification Reactions

Tao

Xue

Sun

et al. 2015

Sci Rep

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In order to investigate the influences of Lewis metals on acidic properties and catalytic activities, a series of Keggin heteropolyacid (HPA) catalysts, HnPW11MO39 (M = TiIV, CuII, AlIII, SnIV, FeIII, CrIII, ZrIV and ZnII; for Ti and Zr, the number of oxygen is 40), were prepared and applied in the esterification and transesterification reactions. Only those cations with moderate Lewis acidity had a higher impact. Ti Substituted HPA, H5PW11TiO40, posse lower acid content compared with TixH3−4xPW12O40 (Ti partial exchanged protons in saturated H3PW12O40), which demonstrated that the Lewis metal as an addenda atom (H5PW11TiO40) was less efficient than those as counter cations (TixH3−4xPW12O40). On the other hand, the highest conversion reached 92.2% in transesterification and 97.4% in esterification. Meanwhile, a good result was achieved by H5PW11TiO40 in which the total selectivity of DAG and TGA was 96.7%. In addition, calcination treatment to H5PW11TiO40 make it insoluble in water which resulted in a heterogeneous catalyst feasible for reuse.

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From designer Lewis acid to designer Brønsted acid towards more reactive and selective acid catalysis

Cited by 32 publications

References 51 publications

Direct Synthesis of Dimethyl Ether from Syngas on Bifunctional Hybrid Catalysts Based on Supported H3PW12O40 and Cu-ZnO(Al): Effect of Heteropolyacid Loading on Hybrid Structure and Catalytic Activity

Direct Synthesis of Dimethyl Ether from Syngas on Bifunctional Hybrid Catalysts Based on Supported H3PW12O40 and Cu-ZnO(Al): Effect of Heteropolyacid Loading on Hybrid Structure and Catalytic Activity

ZnCl2-modified ion exchange resin as an efficient catalyst for the bisphenol-A production

Tailoring the Synergistic Bronsted-Lewis acidic effects in Heteropolyacid catalysts: Applied in Esterification and Transesterification Reactions

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