Catalytic and physico-chemical properties of the Al2O3−H3PO4 system, I. Vapor phase condensation of isobutylene and formaldehyde—The Prins reaction

Krzywicki, A.; Wilanowicz, T.; Malinowski, S.

doi:10.1007/bf02079732

Cited by 21 publications

(16 citation statements)

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“…The activity of the catalysts increases with an increase in H 3 PW 12 O 40 content and gives a satisfactory correlation with the amount of acid sites as determined by TPD-NH 3 (Fig. [8][9][10][11][12][13][14][15] Selectivity towards isoprene and the main by-products changes slightly with variation of the HPA content. Referring to the results of FTIR spectroscopy of adsorbed pyridine, it can be suggested that formaldehyde condensation with isobutene most probably proceeds over the weak Brønsted acid sites of the heteropolyacids, which is line with the earlier observations.…”

Section: Acid Properties Of Supported Hpasmentioning

confidence: 90%

“…7 Therefore the development of a one-step selective process for isoprene synthesis based on heterogeneous catalysts is highly desirable. [8][9][10][11][12][13][14][15] The best results in terms of both conversion and selectivity have been obtained over sulfate and phosphate solid acid catalysts. [8][9][10][11][12][13][14][15] The best results in terms of both conversion and selectivity have been obtained over sulfate and phosphate solid acid catalysts.…”

Section: Introductionmentioning

confidence: 99%

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Isoprene synthesis from formaldehyde and isobutene over Keggin-type heteropolyacids supported on silica

Sushkevich

Ivanova

2016

Catal. Sci. Technol.

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Isoprene synthesis from formaldehyde and isobutene over Keggin-type heteropolyacids supported on silica † V. L. Sushkevich, * a V. V. Ordomsky ab and I. I. Ivanova ac Gas phase Prins condensation of isobutene with formaldehyde has been studied over different Keggin-type heteropolyacids supported on amorphous silica. The catalysts were characterized by elemental analysis, X-ray diffraction, low temperature nitrogen adsorption, TPD of ammonia, FTIR of adsorbed pyridine and NMR spectroscopy. The activity of the supported heteropoly compounds was found to increase in the following order: H 4 SiMo 12 O 40 < H 3 PMo 12 O 40 < H 4 SiW 12 O 40 ≈ H 3 PW 12 O 40 . The lower activity of the supported molybdenum heteropolyacids was attributed to their low thermal stability and partial decomposition during catalyst activation, which resulted in lower acidity. The variation of HPA content from 5 to 33 wt% was also shown to increase catalyst activity. Based on the relationship between the content of weak Brønsted sites, the amount and type of carbonaceous deposits and the catalytic activity, it was concluded that the generation of "working" active sites over HPA catalysts involves the formation of unsaturated branched surface species over weak Brønsted sites. These active carbonaceous species are responsible for selective isoprene synthesis. The best catalyst performance is observed over the catalyst with 20 wt% of H 3 PW 12 O 40 , which shows an isoprene yield of 48% with a selectivity of 63%.Catal. Sci. Technol. This journal is Scheme 1 Two-step process for on-purpose isoprene synthesis from isobutene and formaldehyde.

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Section: Acid Properties Of Supported Hpasmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Isoprene synthesis from formaldehyde and isobutene over Keggin-type heteropolyacids supported on silica

Sushkevich

Ivanova

2016

Catal. Sci. Technol.

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“…The above results spur us on to in-depth investigations of the CeO2 structures with different morphologies. The surface oxygen of a perfect CeO2-rod, which exposes the (110) and (100) crystalline planes, is 9.5 × 10 19 atom per gram, which is three-times (2.9 × 10 19 ) and seven-times (1.4 × 10 19 ) the values for a perfect cube and Combined with the catalytic performances, Lewis acid site concentration, and oxygen vacancy concentration ( Figure 5), we found an increase in FA conversion when changing the shape of CeO2. The CeO2-rod shows the best FA conversion because of its having the highest concentration of Lewis acid sites and oxygen vacancies among the three morphologies investigated.…”

Section: Effect Of Crystalline Planementioning

confidence: 99%

“…The above results spur us on to in-depth investigations of the CeO 2 structures with different morphologies. The surface oxygen of a perfect CeO 2 -rod, which exposes the (110) and (100) crystalline planes, is 9.5 × 10 19 atom per gram, which is three-times (2.9 × 10 19 ) and seven-times (1.4 × 10 19 ) the values for a perfect cube and octahedron, respectively [23], implying the probability that oxygen vacancy formation for CeO 2 -rod is higher than that for cube and octahedron. DFT calculations have proven that the formation energies of oxygen vacancies for different CeO 2 surfaces follow the order of (110) < (100) < (111) [33], meaning that the order of intrinsic oxygen vacancy formation follows (110) > (100) > (111).…”

Section: Preparation Of the Ceo2 Catalystsmentioning

confidence: 99%

“…In the synthesis route, both the Prins condensation and hydrolysis reaction require acid catalysts [3,15,16]. Various solid acid catalysts, such as metal oxide catalysts [17], zeolite catalysts [18], phosphate catalysts [15,19,20], and heteropolyacids catalysts [21,22], have been developed for the two-step reaction (Prins condensation and hydrolysis reaction). Alternatively, a single-stage 3-methyl-1,3-butanediol synthesis from isobutene and HCHO in water is one interesting route to be investigated, and a water-tolerant acid catalyst is critical.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of 1,3-Diols from Isobutene and HCHO via Prins Condensation-Hydrolysis Using CeO2 Catalysts: Effects of Crystal Plane and Oxygen Vacancy

et al. 2017

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Abstract:We herein report the synthesis of 3-methyl-1,3-butanediol from isobutene and HCHO in water via a Prins condensation-hydrolysis reaction over CeO 2 , which is a water-tolerant Lewis acid catalyst. The CeO 2 exhibits significant catalytic activity for the reaction, giving 95% HCHO conversion and 84% 3-methyl-1,3-butanediol selectivity at 150 • C for 4 h. The crystal planes of CeO 2 have a significant effect on the catalytic activity for the Prins reaction. The (110) plane shows the highest catalytic activity among the crystal planes investigated (the (100), (110), and (111) planes), due to its higher concentration of Lewis acid sites, which is in line with the concentration of oxygen vacancies. Detailed characterizations, including NH 3 -TPD, pyridine-adsorbed FT-IR spectroscopy, and Raman spectroscopy, revealed that the concentration of Lewis acid sites is proportional to the concentration of oxygen vacancies. This study indicates that the Lewis acidity induced by oxygen vacancy can be modulated by selective synthesis of CeO 2 with different morphologies, and that the Lewis acidity and oxygen vacancy play an important role in Prins condensation and hydrolysis reaction.

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Catalysis by Coke Deposits: Synthesis of Isoprene over Solid Catalysts

2013

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Nützlicher „Abfall“: Kohlenstoffhaltige Ablagerungen spielen eine zentrale Rolle bei der selektiven heterogenkatalytischen Synthese von Isopren aus Formaldehyd und Isobuten. Sie reichern sich während der Induktionsperiode an der Katalysatoroberfläche an und fördern die Wechselwirkung der Substrate im stationären Zustand. Der postulierte Mechanismus (siehe Schema) dient als Ansatzpunkt für den gezielten Entwurf fester Katalysatoren für die Isoprensynthese.

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Catalytic and physico-chemical properties of the Al2O3−H3PO4 system, I. Vapor phase condensation of isobutylene and formaldehyde—The Prins reaction

Cited by 21 publications

References 2 publications

Isoprene synthesis from formaldehyde and isobutene over Keggin-type heteropolyacids supported on silica

Isoprene synthesis from formaldehyde and isobutene over Keggin-type heteropolyacids supported on silica

Synthesis of 1,3-Diols from Isobutene and HCHO via Prins Condensation-Hydrolysis Using CeO2 Catalysts: Effects of Crystal Plane and Oxygen Vacancy

Catalysis by Coke Deposits: Synthesis of Isoprene over Solid Catalysts

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