The direct synthesis of hydrogen peroxide from H ₂ and O ₂ using Pd–Ni/TiO ₂ catalysts

Abstract

<jats:p> The direct synthesis of hydrogen peroxide (H <jats:sub>2</jats:sub> O <jats:sub>2</jats:sub> ) from molecular H <jats:sub>2</jats:sub> and O <jats:sub>2</jats:sub> offers an attractive, decentralized alternative to production compared to the current means of production, the anthraquinone process. Herein we evaluate the performance of a 0.5%Pd–4.5%Ni/TiO <jats:sub>2</jats:sub> catalyst in batch and flow reactor systems using water as a solvent at ambient temperature. These reaction conditions are considered challenging for the synthesis of high H <jats:sub>2</jats:sub> O <jats:sub>2</jats:sub> concentrations, with the use of sub-ambient temperatures and alcohol co-solvents typical. Catalytic activity was observed to be stable to prolonged use in multiple batch experiments or in a flow system, with selectivities towards H <jats:sub>2</jats:sub> O <jats:sub>2</jats:sub> of 97% and 85%, respectively. This study was carried out in the absence of halide or acid additives that are typically used to inhibit sequential H <jats:sub>2</jats:sub> O <jats:sub>2</jats:sub> degradation reactions showing that this Pd–Ni catalyst has the potential to produce H <jats:sub>2</jats:sub> O <jats:sub>2</jats:sub> selectively. </jats:p> <jats:p>This article is part of a discussion meeting issue ‘Science to enable the circular economy’.</jats:p>

Enhancing catalytic performance of AuPd catalysts towards the direct synthesis of H2O2 through incorporation of base metals

“…Although in recent years great strides have been made in improving catalyst selectivity through the incorporation of numerous secondary metals into supported Pd catalysts. Perhaps most extensively studied has been the enhancement in catalytic efficacy through the alloying of Pd with Au, [8][9][10][11][12] however numerous investigations have demonstrated that the addition of a range of abundant metals including Fe, 13,14 Sn, 15,16 Ni, 17,18 In, 19 Ag, 20 Zn, 21,22 Te 23 and Co 24 can similarly enhance catalytic performance. Further studies have focussed on the incorporation of dopant levels of precious metals, in particular Pt, into supported Pd, [25][26][27][28] Au 29 and AuPd catalysts.…”

Facile synthesis of Pd–Au/BNNS bimetallic catalysts for direct generation of H2O2 from H2 and O2 under environmentally friendly conditions

“…23 In addition, the activity of monometallic and bimetallic catalysts can be improved by selecting more suitable support materials such as TiO 2 , carbon-based substrates, zeolites, γ-Al 2 O 3 , hydroxyapatite (HAp), mesoporous alumina, amorphous silica-alumina, etc. [24][25][26][27][28] For example, Wang et al have employed a porous hypercrosslinked ionic polymer as an efficient support for the immobilization of Pd nanoparticles and employed this catalyst in the heterogeneous aerobic oxidative coupling of diaryl ethers. 29 In the present study, boron nitride nanosheets because of their excellent properties such as high surface area, high mechanical strength, and chemical and thermal stability, were an excellent choice as the support for uniform stabilization of Pd-Au nanoparticles.…”

The degradation of phenol via in situ H2O2 production over supported Pd-based catalysts

“…8,11,12 However, due to limited selectivity there is often a need to alloy Pd with a range of precious metals, [13][14][15][16][17] although in recent years, a growing attention has been placed on the use of more abundant transition metals as promoters for Pd. [18][19][20][21][22][23] Indeed, we have recently demonstrated the ability of bi-functional Pdbased bimetallic nanoparticles to catalyse the direct synthesis of H 2 O 2 in addition to the selective oxidation of a range of substrates [24][25][26] as well as the remediation of microorganisms through radical pathways. 27 With these studies in mind, we now investigate the efficacy of supported Pd-based bimetallic catalysts that combine the H 2 O 2 synthesising activity of Pd and the ability of a range of transition metals to generate reactive oxygen species through Fenton's pathways for the degradation of phenol.…”