Thermo‐Photocatalytic Methanol Reforming for Hydrogen Production over a CuPd−TiO₂ Catalyst

Abstract

A bimetallic CuPd/TiO2 system has been prepared by a two‐step synthesis and was used for a methanol steam photoreforming reaction. By sequential deposition, palladium is deposited over copper nanoclusters through a galvanic replacement process. Hydrogen production by steam reforming from methanol was achieved by both thermo‐photocatalytic and photocatalytic processes. It appears that H2 production on the bimetallic system is notably higher than the Pd monometallic reference. Moreover this difference in the catalytic performance could be related to the higher CO evolution observed for the monometallic Pd1.0 TiO2 system which is partially inhibited in the bimetallic catalyst. In addition, an important thermal effect can be envisaged in all cases. Nevertheless, this improved effect in the thermo‐photocatalytic process is accompanied by a remarkable CO evolution and SMSI effect (important strong metal‐support interactions) that hindered the efficiency as temperature increases. On this basis, optimal operational conditions for H2 production are obtained for thermo‐photocatalytic reforming at 100 °C, for which the synergetic effect is higher with lower CO production (H2/CO=4).

Mechanistic Considerations on the H2 Production by Methanol Thermal‐assisted Photocatalytic Reforming over Cu/TiO2 Catalyst

“…This behavior is significantly different from a previous study for Pd,Cu bimetallic system. [ 22] In that case, the presence of Pd clearly favors the CO evolution even at high temperatures. Therefore, although CuPd bimetallic catalysts show lower photonic efficiencies than Pd monometallic one, the notably lower CO produced would lead a better candidate for this reaction.…”

“…[20,21] Within this context, we reported in a previous paper an interesting approach to methanol steam reforming by combining heating and photonic excitation using PdÀ Cu supported TiO 2 as catalyst. [22] For this bimetallic system, optimal operational condition for H 2 production is attained through thermophotocatalytic reforming at 100°C, for which the synergistic effect is higher with lower carbon monoxide production (H 2 / CO = 4). At higher temperature, although the H 2 yield is higher, carbon monoxide evolution becomes important.…”

Main Hydrogen Production Processes: An Overview

“…On the other hand, copper was successful used as promoter to increase the selectivity of Pd-based catalysts in methanol steam reforming [34]. The CuPd/TiO 2 bimetallic catalytic system showed improved performance, with respect the monometallic counterpart, by both thermo-photocatalytic and photocatalytic processes [35].…”

High-efficient and Low-cost H2 Production by Solar-driven Photo-thermo-reforming of Methanol with CuO Catalyst

“…The peaks located at 931.8 and 952.7 eV could belong to the Cu (1) or Cu (0) after 30-min reaction. [32] Indeed, from the Cu LMM Auger of CuO after 30 min reaction it is predictable that only Cu (0) exists. UV-Vis diffuse reflection was used to characterize the light absorbability of the fresh CuO and used CuO.…”

“…[29,30] In addition, Cu-based catalysts have shown excellent performance for H2 production by methanol thermo-reforming [31] and methanol photo-reforming. [32,33] In general, the oxidation states of copper (i.e., Cu (0) , Cu + , and Cu 2+ ) can be varied under UV irradiation. [34][35][36] Fig.…”