Synthesis of Mesoporous Nickel-Ceria Catalyst Using Tri-Block Co-Polymer Template for Low–Temperature Water-Gas-Shift Reaction

Abstract:

Recently, the water-gas shift reaction has become very important because of its potential use in conjunction with fuel cell power generation and production of high purity H₂

. It has been reported that novel metal supported on ceria is a superior catalyst for the water-gas shift reaction. Ceria is also a crucial component of automotive three-way emission control catalysts. Self-assembly of block copolymers provides a versatile approach to the creation of nanostructured materials. Mesoporous inorganic materials, templated by tri-block copolymer self assemblies usually have high surface areas, which promising for catalytic applications.

Mesoporous cerium oxide and nickel-loaded cerium oxide catalysts were synthesized by evaporation-induced self-assembly (EISA) followed by direct calcination to remove the polymer template. A novel tri-block copolymer of different length ratio was used as a template directing agent. Nickel was added to the mesoporous cerium oxide support by incipient wetness impregnation method. Lanthanum (10 at. %) was used as a stabilizing agent of cerium oxide support. The catalysts were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis and N₂ physisorption. The BET results showed that the surface areas of the catalysts significantly increased due to the addition of lanthanum to the nickel-cerium oxide. The X-ray diffraction revealed that the crystal size and structure were extremely sensitive to the conditions of heat treatment. The catalytic activity for the low temperature water-gas shift reaction was evaluated over nickel-doped and undoped cerium-lanthanum oxide catalysts in a tubular flow reactor. The temperature of the reaction was varied from 150 to 350^oC

. The flow rate and other reaction condition were optimized. The experimental results showed that the catalytic activities of cerium-lanthanum oxide catalysts were significantly increased by the addition of small amount of nickel.