Barry W. L. Southward

The effect of the addition of sodium compounds in the liquid-phase hydrodechlorination of chlorobenzene over palladium catalysts

Abstract The hydrodechlorination of chlorobenzene over supported palladium catalysts has been studied. The palladium catalysts deactivate as the reaction proceeds due to the HCl formed as by-product. The effect of the addition of sodium compounds has been analysed for the neutralisation of HCl. When NaOH was added to the reaction mixture, no beneficial effect was observed due to the detrimental effect of the alkaline medium on the textural and metallic properties of the catalysts. Doping the support with NaOH prior to impregnation with the metal precursor leads (after calcination and reduction) to catalysts with better activity and tolerance to deactivation, especially those obtained when using PdCl 2 as the metal precursor. Low metal dispersion and the capture of chloride by forming NaCl are the main factors contributing to the improved catalytic properties. Finally, doping the catalysts with NaOH or NaNO 3 , after reduction of the metal precursor leads to a moderate increase in initial activity and final conversion, although NaOH impregnation also gave rise to support corrosion and metal dispersion modification.

An investigation of the selective oxidation of NH3 to N2 in gasified biomass in the presence of excess CO and H2 using zeolite catalysts

The selective oxidation of NH3 to N2 in simulated biogas containing a large excess of CO and H2 has been examined using zeolite catalysts. Of the materials examined zeolite Beta gave the highest N2 yield (85% at 475–575°C), while ZSM5 produced 75% at 575°C, but HY was both less active and selective. In all cases N2 is formed via an internal selective catalytic reduction between NOx (derived from the oxidation of NH3) and NH3 adsorbed on Brønsted sites of the zeolite.

The effect of SO2 on the activity of Pd-based catalysts in methane combustion

The effect of SO2 on Pd-based catalysts for the combustion of methane has been investigated. It is shown that while SO2 poisons Al2O3- and SiO2-supported catalysts, pre-treatment of Pd/ZrO2 by SO2 enhances the activity substantially.

The effect of pre-sulfiding of catalysts for the vapour phase catalytic synthesis of thiophenes

A study of catalyst pre-sulfiding for the synthesis of 3-methylthiophene from 2-methylbutanol and carbon disulfide over potassium-promoted chromia–alumina has been performed. Pretreatment with CS2 results in enhancements in 3MT yield and catalyst lifetime. The benefits observed are ascribed to a combination of enhanced Cr2S3 formation and poisoning of sites responsible for side reactions which limit selectivity and result in the formation of deactivating by-products.

Novel catalysts for thiophene synthesis at lower temperatures

Thiophenes can be synthesised in high yields from the reaction of C4+ oxygenates and CS2 at temperatures 140 °C lower than current industrial catalysts, using novel materials based upon chromium substituted iron oxide hydroxide.

Low-temperature, clean catalytic combustion of N-bearing gasified biomass using a novel NH3 trapping catalyst

Substantially reduced NOx emissions are nobtained in the low temperature catalytic combustion of nNH3-bearing simulated biogas by use of a novel n1%Pt/20%CuO/Al2O3-trapping catalyst and cyclic noperation between fuel lean and rich conditions.

Novel alkaline earth supported catalysts for thiophene synthesis

3-Methylthiophene can be synthesised in yields >95 mol% from the reaction of 2-methylbutanol and CS2 over MgO-supported potassium-promoted ‘Fe0.95Cr0.05OOK’; catalysts using γ-Al2O3 or other alkaline earth oxides as supports are less effective.

Clean catalytic combustion of nitrogen-bearing gasified biomass

Zero NOx emissions are obtained nin the catalytic combustion of simulated biomass mixtures containing nsubstantial amounts of ammonia by optimisation of NH3 oxidation nand NOx reduction using a n2%Rh–Al2O3 catalyst.

A method for obtaining stable, high activity for NOx reduction at low temperatures

Very high and stable low temperature activity for the reduction of NO by n-octane on a 0.3 mass% Pt/Al2O3 catalyst operating under lean burn conditions may be achieved by secondary injection of micropulses of clean-burning thermal promoters into the gas stream.