Confined Ni-In intermetallic alloy nanocatalyst with excellent coking resistance for methane dry reforming

Carbon dioxide and methane are two main greenhouse gases which are contributed to serious global warming. Fortunately, dry reforming of methane (DRM), a very important reaction developed decades ago, can convert these two major greenhouse gases into value-added syngas or hydrogen. The main prob-lem retarding its industrialization is the seriously coking formation upon the nickel-based catalysts. Herein, a series of confined indium-nickel (In-Ni) intermetallic alloy nanocatalysts (InxNi@SiO2) have been prepared and displayed superior coking resistance for DRM reaction. The sample containing 0.5 wt.% of In loading (In0.5Ni@SiO2) shows the best balance of carbon deposition resistance and DRM reac-tivity even after 430 h long term stability test. The boosted carbon resistance can be ascribed to the con-finement of core-shell structure and to the transfer of electrons from Indium to Nickel in In-Ni intermetallic alloys due to the smaller electronegativity of In. Both the silica shell and the increase of electron cloud density on metallic Ni can weaken the ability of Ni to activate C-H bond and decrease the deep cracking process of methane. The reaction over the confined InNi intermetallic alloy nanocata-lyst was conformed to the Langmuir-Hinshelwood (L-H) mechanism revealed by in situ diffuse reflec-tance infrared Fourier transform spectroscopy (in-situ DRIFTS). This work provides a guidance to design high performance coking resistance catalysts for methane dry reforming to efficiently utilize these two main greenhouse gases. (c) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.