Engineering the TiO<sub><i>x</i></sub> Overlayer on Ni Catalyst to Balance Conversion and Stability for Methane Dry-CO<sub>2</sub> Reforming
Xueqin Bai, Xueli Yao, Qingpeng Cheng, Hend Omar Mohamed, Selvedin Telalović, Georgian Melinte, Abdul‐Hamid Emwas, Jorge Gascón, Pedro Castaño
Abstract
High Resolution Image Download MS PowerPoint Slide Ni-supported catalyst is a viable system to convert methane and carbon dioxide into syngas through methane dry reforming, with the main drawbacks of its fast deactivation being sintering and coking. Here, we developed methods to engineer a TiO x overlayer on Ni/TiO 2 catalysts to shield the catalyst against sintering and coking while preserving the Ni accessibility and, thus, conversion. These methods involved altering TiO 2 crystal phases, pretreatment, and reaction conditions in the reforming stage. Through characterization, testing, and operando spectroscopy, we found that the TiO x overlayer with incomplete Ni coverage maintained a balanced conversion and stability by quenching the sintering and coking. Conversely, thick or nonexistent overlayers led to lower conversions or faster deactivation. The formation of TiO x overlayer increased the CO 2 activation capacity and oxygen mobility and protected Ni from sintering by its shield function. At the same time, the reaction pathways remained unchanged despite the TiO x overlayer with different morphologies.