The direct synthesis of hydrogen peroxide (H2O2) from H2 and O2 represents a potentially atom-efficient alternative to the current industrial indirect process. We show that the addition of tin to palladium catalysts coupled with an appropriate heat treatment cycle switches off the sequential hydrogenation and decomposition reactions, enabling selectivities of >95% toward H2O2. This effect arises from a tin oxide surface layer that encapsulates small Pd-rich particles while leaving larger Pd-Sn alloy particles exposed. We show that this effect is a general feature for oxide-supported Pd catalysts containing an appropriate second metal oxide component, and we set out the design principles for producing high-selectivity Pd-based catalysts for direct H2O2 production that do not contain gold.

Globally, water disinfection is reliant on chlorination but a route that avoids the formation of chemical residues would be preferred. Hydrogen peroxide, can offer such an alternative, is a broad-spectrum biocide but typically is less effective than traditional approaches to water remediation. Here, we show that the reactive species-including hydroxyl, hydroperoxyl and superoxide radicals-formed over a AuPd catalyst during the synthesis of hydrogen peroxide from hydrogen and air are over 10 7 times more potent than an equivalent amount of pre-formed hydrogen peroxide and over 10 8 times more effective than chlorination under equivalent conditions. The key to bactericidal and virucidal efficacy is the radical flux that forms when hydrogen and oxygen are activated on the catalyst. This approach can form the basis of an alternative method for water disinfection particularly in communities not currently served by traditional means of water remediation or where access to potable water is scarce.

Pt/KL is the widely accepted catalyst for aromatizing n-hexane by 1,6 ring closure but encounters deactivation issues when aromatizing higher carbon-number feeds; undergoing extensive dealkylation to give unwanted CH4 and unselective products, as well as over-aromatization to form coke. Here, we report the use of a non-acidic MFI zeolite support, containing excess K + beyond ion exchange capacity, well dispersed Pt, and high Pt presence inside the pores, for maximising direct n-alkane aromatization selectivity. TGA, catalyst deactivation studies, and characterizations show that the smaller pore sizes and lack of large cages in the MFI support sterically inhibit coke formation inside the pores (0% compared to 4.9% over Pt/KL for n-octane aromatization), which also reduces dealkylation of ethylbenzene and o-xylene under mild conditions to give a more selective product distribution, 86% selectivity by weight towards C6 ring closure compared to 27% for Pt/KL. Additionally, using NH3-TPD, XPS,CO-DRIFTS, and STEM, we show the contribution of excess K + as an inhibitor of strong acid sites, an indirect Pt electron promoter through improving metal support interaction, and Pt dispersant. This work highlights the alternative use of well-understood zeolitic supports for the highly selective aromatization of n-heptane and n-octane by 1,6 ring closure, increasing the number of potential streams that can undergo direct aromatization, and providing a suitable alternative to Pt/KL.

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Pt–Zn bimetallic nanoparticles show unique performance towards n-alkane direct aromatization and isomerization only when dispersed on a uniform cylindrical ZSM-5 support.