Unravelling water effects on solid acid catalysts: Case study of TiO 2 /SiO 2 as a catalyst for the dehydration of isobutanol

Abstract

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Supported oxides catalysts for the dehydration of isobutanol into butenes: Relationships between acidic and catalytic properties

“…It revealed that amorphous SnO 2 clusters were reduced to Sn crystalline particles under isobutanol vapour at 300 °C leading to dehydrogenating activity. High conversion (89.3%) and very high selectivity to butenes (97.4%) was obtained using 20.4%TiO 2 /SiO 2 -G after 4 h. Such feature was in agreement with data obtained in the same conditions of temperature and contact time but with a diluted feed iC 4 OH/inert: 35/65 [44]. The isomerisation activity was slightly higher than the SiO 2 -G one (S LinBut 33% instead of 30%) and close to values reported in the literature for mixed oxides [24].…”

“…The isomerisation activity was slightly higher than the SiO 2 -G one (S LinBut 33% instead of 30%) and close to values reported in the literature for mixed oxides [24]. It is worth noting that a value of 33% was also measured at 300 °C for feed composition iC 4 OH/inert 35/65 and 1/WHSV 0.30 h [44]. After 20 h on stream, the conversion was lowered to 64.8% which corresponded to a faster deactivation than for a diluted feed [44].…”

“…The two catalysts were initially less selective to butenes than 20.4%TiO 2 /SiO 2 -G because of C5+ products formation but became very selective after 20 h (>98% of butenes). The S LinBut values measured for the two catalysts were similar, almost constant and the highest among the screened catalysts indicating both that the linear butenes were mainly formed from thermodynamic equilibrium between the four carbocations [44] and that another less favourable isobutene isomerisation route was activated. (Figure 7).…”

“…It is worth noting that a value of 33% was also measured at 300 °C for feed composition iC 4 OH/inert 35/65 and 1/WHSV 0.30 h [44]. After 20 h on stream, the conversion was lowered to 64.8% which corresponded to a faster deactivation than for a diluted feed [44].…”

Selective hydrogenolysis of 5-hydroxymethylfurfural to 2,5-dimethylfuran over Co3O4 catalyst by controlled reduction

“…At the reduction temperature of 500 °C, the catalyst showed no obvious peaks detected, indicating the most of Co 3 + were reduced into Co metal. The NH 3 -TPD results showed that in low reduction temperature, most of the Lewis sites of Co 3 O 4 were weak, since NH 3 as a strong base was able to react with them to form ammonium cations [33] . The atom percentage of O and Co elements was calculated by using EDS analysis during TEM measurements and the results are summarized in Table 2 .…”