No abstract

Propylsulfonic acid (PrSO3H) derivatised solid acid catalysts have been prepared by post‐modification of mesoporous SBA‐15 silica with mercaptopropyltrimethoxysilane (MPTMS), and the impact of co‐derivatisation with octyltrimethoxysilane (OTMS) groups to impart hydrophobicity to the catalyst was investigated. Turnover frequencies (TOFs) for acetic acid esterification with methanol increase with PrSO3H surface coverage across both families, suggesting a cooperative effect between adjacent acid sites at high acid site densities. Esterification activity is further promoted upon co‐functionalisation with hydrophobic octyl chains, with inverse gas chromatography (IGC) measurements indicating that the increased activity correlates with decreased surface polarity or increased hydrophobicity.

No abstract

Highlights  Niobium-containing SBA-15 silica used as catalysts for a model reaction to biodiesel production.  High niobium content and high calcination temperature maintained SBA-15 mesoporous silica profile.  Solid evaluated as catalyst with low Nb concentration (2 wt.%) showed better catalytic performance.  Nb promoter effect: catalyst stability at low loadings and also lowest heating treatment.

A family of tungstated zirconia solid acid catalysts were synthesised via wet impregnation and subsequent thermochemical processing for the transformation of glucose to 5-hydroxymethylfurfural (HMF). Acid strength increased with tungsten loading and calcination temperature, associated with stabilisation of tetragonal zirconia. High tungsten dispersions of between 2 and 7 W atoms·nm −2 were obtained in all cases, equating to sub-monolayer coverages. Glucose isomerisation and subsequent dehydration via fructose to HMF increased with W loading and calcination temperature up to 600 °C, indicating that glucose conversion to fructose was favoured over weak Lewis acid and/or base sites associated with the zirconia support, while fructose dehydration and HMF formation was favoured over Brönsted acidic WOx clusters. Aqueous phase reforming of steam exploded rice straw hydrolysate and condensate was explored heterogeneously for the first time over OPEN ACCESSCatalysts 2014, 4 415 a 10 wt% WZ catalyst, resulting in excellent HMF yields as high as 15% under mild reaction conditions.

The first application of WS 2 , a well-known graphene analogue, as a solid acid catalyst for carboxylic acid esterification is reported. WS 2 exhibits excellent specific activities and high conversion to methyl esters of (65-90 %) for C2-C16 carboxylic acid esterification with methanol under mild conditions, with Turnover Frequencies between 80-180 h -1 , and outstanding water tolerance even under equimolar water spiking. WS 2 also exhibits good stability towards methyl propanoate in the continuous esterification of propanoic acid, and is a promising candidate for biofuels production.

No abstract

No abstract