Hydrogen Production through Water–Gas Shift Reaction over Supported Cu, Ni, and CuNi Nanoparticle Catalysts Prepared from Metal Colloids

Abstract

Colloidal Cu, Ni, and CuNi nanoparticles obtained through chemical reduction were impregnated onto γ‐Al2O3 to prepare supported catalysts. Conventional catalysts were also prepared for comparison through support impregnation with metal salt solutions. A combination of TEM and STEM, thermogravimetric analysis, powder X‐ray diffraction, X‐ray photoelectron spectroscopy, and N2 adsorption analysis was used to characterize the alumina‐supported nanoparticle catalysts. Monodisperse Cu and Ni nanoparticles were uniformly distributed on γ‐Al2O3 as observed by STEM equipped with a high‐angle annular dark field (HAADF) detector. The powder XRD and HAADF–STEM provided evidence supporting the formation of CuNi particles containing the Cu core and the CuNi alloy shell. The resulting supported Cu and Ni nanoparticle catalysts were found to be 2.5 times more active in the water–gas shift (WGS) reaction per unit mass of the active metal as compared with catalysts prepared by means of the conventional impregnation method. Supported Cu catalysts showed promising activity at low temperatures (125–250 °C), whereas supported Ni catalysts showed high activity at high temperatures (275–400 °C). The presence of a surfactant during the preparation of supported Cu nanoparticles resulted in a higher degree of Cu dispersion and thus enhanced WGS activity. Stabilized Ni/Ni(OH)2 nanoparticles were also synthesized to prepare well‐dispersed supported Ni catalysts. In the case of bimetallic catalysts, Cu5Ni5 catalysts showed a higher specific reaction rate per unit surface area of the active metal than did monometallic catalysts. These findings strongly suggested that supported Cu, Ni, and CuNi nanoparticle catalysts prepared from metal colloids are promising, highly active WGS catalysts.

Ni-CeO2/C Catalysts with Enhanced OSC for the WGS Reaction

“…This catalyst quadruplicates the activity of the Ni/CeO2 solid at 240 °C, and reaches equilibrium conversion at 260 °C. Compared to others Ni-ceria catalysts previously reported, our carbon-supported sample performs better even under harder WGS conditions [17,18]. This is a very promising result since this material seems to be as efficient as some well-known noble metal based catalysts for this reaction [19].…”

Carbon nanotube-supported Ni–CeO2 catalysts. Effect of the support on the catalytic performance in the low-temperature WGS reaction

“…Furthermore, by using Feed C methane formation was observed although only at temperatures above 573 K, and it was mainly due to CO 2 hydrogenation, as no methane was observed when the CO 2 -free feed stream was used, together with the presence of a high concentration of H 2 [27]. The lower catalytic activity under these conditions can be due to the larger amount of CO in the feed stream although, additionally, and according to literature, both CO 2 and H 2 can also have a negative effect in the WGS reaction rate [40]. While CO 2 may produce carbonates on the ceria surface [ 41 , 42 ], an excess of hydrogen may lead to the irreversible over-reduction of ceria [43].…”

Role of Metal–Support Interactions, Particle Size, and Metal–Metal Synergy in CuNi Nanocatalysts for H2 Generation

“…Meanwhile, the XPS spectra of Ni 2p contain the main peaks attributable to Ni 2+ with the binding energy of Ni 2p 3/2 and Ni 2p 1/2 at 855.5 and 872.5 eV, respectively ( Figure 3). 55 Recently, catalytic hydrolysis of AB (H 3 NBH 3 + 2H 2 O → NH 4 + + BO 2 − + 3H 2 ) and decomposition of hydrazine have received considerable research interest as potential approaches towards hydrogen energy-based systems. [32][33][34] Moreover, these processes have been used widely as adequate model reactions to study the catalytic properties of novel catalysts.…”