The alkylation of benzene by propane to yield isopropylbenzene (iPrPh) was studied using bifunctional Pd-acid catalysts, such as Pd-heteropoly acid and Pd-zeolite, in a fixed bed reactor at 300 °C and 1 bar pressure. Keggin-type tungstosilicic acid H₄SiW₁₂O₄₀ (HSiW) and zeolite HZSM-5 were used as the acid components in these catalysts. The reaction occurred most efficiently over 2%Pd/25%HSiW/SiO₂, giving iPrPh with up to 88% selectivity. The Pd-HSiW catalyst was more selective than the Pd-HZSM-5; the latter gave only 11–18% iPrPh selectivity. The reaction proceeded via a bifunctional mechanism including the dehydrogenation of propane to form propene on Pd sites, followed by the alkylation of benzene with the propene on acid sites. The effect of Pd loading in Pd-HSiW and Pd-HZSM-5 catalysts indicated that the first step reached quasi-equilibrium at 1.5–2% Pd loading and the second step became rate limiting. The addition of gold to Pd-HSiW enhanced the activity of this catalyst, although the Au-HSiW without Pd was inert.

Hydroconversion (hydrogenation and hydrogenolysis) of biomass-derived furanic compounds giving furan ring-hydrogenation and ring-cleavage products attracts interest for sustainable production of chemicals and fuels. Here, the hydroconversion of 2,5-dimethylfuran (DMF), chosen as a model furanic compound, was investigated at a gas-solid interface over carbon-supported Pt, Pd, Rh and Ru metal catalysts in a fixed-bed reactor at 70–90 °C and ambient pressure. Pt/C was mainly active in ring cleavage of DMF to produce 2-hexanone as the primary product, followed by its hydrogenation to 2-hexanol and hexane. In contrast, Pd/C, Rh/C and Ru/C selectively hydrogenated the furan ring to 2,5-dimethyltetrahydrofuran (DMTHF). The turnover frequency (TOF) of metal sites in the gas-phase DMF hydroconversion was determined from zero-order kinetics in the absence of diffusion limitations. The TOF values decreased in the sequence Pt > Rh > Pd >> Ru, similar to the liquid-phase reaction. The TOF values for the gas-phase reaction were found to be one order of magnitude greater than those for the liquid-phase reaction. This indicates that the gas-phase process is potentially more efficient than the liquid-phase process. TOF values for hydroconversion of ring-saturated furan derivatives, tetrahydrofuran and DMTHF, on Pt/C, were much lower than those for DMF.

Silica-supported zinc oxide possessing acid and dehydrogenation functions is an efficient, noble-metal-free bifunctional catalyst for the environment-friendly synthesis of p-Cymene from renewable monoterpene feedstock by gas-phase dehydroisomerisation of α-pinene and limonene in a fixed-bed reactor. The reaction involves acid-catalysed terpene isomerisation to p-menthadienes followed by dehydrogenation to form p-Cymene. Dehydroisomerisation of α-pinene produces p-Cymene with 90% yield at 100% conversion at 370 °C and WHSV = 0.01–0.020 h⁻¹. The reaction with limonene gives a 100% p-Cymene yield at 325 °C and WHSV = 0.080 h⁻¹. ZnO/SiO₂ catalyst shows stable performance for over 70 h without co-feeding hydrogen.

Dehydration of i-PrOH is used in academic research as a test reaction to probe the acid properties of solid acid catalysts. Also, it has practical importance for the utilization of surplus acetone produced by the Hock process for the combined manufacturing of phenol and acetone as well as for the production of propene from renewable resources and waste. This study demonstrates the excellent performance of polyoxometalate acid catalysts comprising silica-supported Keggin-type heteropoly acids H₃PW₁₂O₄₀ and H₄SiW₁₂O₄₀ for gas-phase i-PrOH-to-propene dehydration at ambient pressure. These catalysts show similar efficacies, giving an i-PrOH conversion and propene selectivity of 96.8 and 99.7% for 25%HPW/SiO₂ and 97.1 and 99.4% for 25%HSiW/SiO₂ in a fixed-bed reactor at 120 °C, a relevant-to-practice i-PrOH partial pressure of 15 kPa and a contact time W/F = 27 g h mol⁻¹ (GHSV = 900 mL g⁻¹ h⁻¹). The catalysts are stable, resisting deactivation for at least 24 h time on stream. The HPA/SiO₂ catalysts are superior to aluminosilicate zeolites such as H-mordenite, HZSM-5 and HY for i-PrOH-to-propene dehydration in terms of i-PrOH conversion, propene selectivity and catalyst stability.

Aerobic oxidative desulfurization (ODS) of model liquid fuel (dodecane spiked with dibenzothiophene (DBT)) was carried out in the presence of bulk and supported Keggin-type heteropoly acids H_3+nPMo_12-nV_nO₄₀ (HPA-n, n = 0–3) as heterogeneous catalysts and benzaldehyde as a sacrificial reductant. In the presence of bulk H₄PMo₁₁VO₄₀ (HPA-1), 100% of DBT was removed from fuel (converted to DBT sulfone) at 60 °C and ambient air pressure. Multiple catalyst reuse without loss of activity was demonstrated. The ODS reaction was strongly inhibited by radical scavengers. An unbranched radical chain mechanism was proposed.