Effect of cerium dioxide on the properties of monolithic CuO-ZnO-CeO2/Al2O3/cordierite catalysts in methanol decomposition

Abstract

Cerium dioxide as a component of CuO-ZnO-CeO 2 /Al 2 O 3 /cordierite catalysts stabilizes their action in the decomposition of methanol by preventing carbon deposition on the surface and facilitating hydrogen formation with selectivity and yield in the range 85-96%. The optimal indices for this reaction are obtained for a CeO 2 -CuO/Al 2 O 3 /cordierite sample prepared using an ammonium precursor for cerium, (NH 4 ) 2 Ce (NO 3 ) 6 . This catalyst displays enhanced reductive capacity relative to the analogous CeO 2 -CuO composition prepared using Ce (NO 3 The ever increasing interest in hydrogen as a fuel, including application in transport vehicles, has led to a search for efficient and safe methods for the storage of this gas. Since the problem of developing absorbents capable of the reversible absorption and desorption of hydrogen without change in their physical characteristics has not yet been solved, the use of hydrogen obtained from a fuel source by reforming in situ is considered the best practical solution [1]. Methanol has high energy density (H : C = 4 : 1) and may be prepared relatively simply from natural gas, coal, and biomass. This inexpensive liquid is among the most promising hydrogen fuel carriers.Reforming methanol to give hydrogen is carried out by decomposition, steam and oxygen conversion, including combinations of these methods under autothermal conditions [2].In the present work, we studied the decomposition of methanol (CH 3 OH = CO + 2H 2 , ÄH 0 = +91 kJ/mol), which holds interest as an alternative method for its use as a fuel for internal combustion engines (utilizing synthesis gas or as an additive to gasoline fuel mixtures) [1], as a heat recovery in industry (since it is an endothermic reaction), and as a hydrogen source for high-temperature solid oxide fuel cells (SOFC) [3].The search for active and selective catalysts for methanol decomposition (MD) is carried out from the viewpoint of the reverse reaction to methanol synthesis from CO and H 2 . Thus, systems with composition similar to Cu-ZnO catalysts for methanol synthesis from synthesis gas, hold high interest [4,5].In the present work, we studied the decomposition of methanol on CuO-ZnO-CeO 2 /Al 2 O 3 catalysts supported on monolithic ceramic matrices with honeycomb structure, namely, synthetic cordierite, 2MgO·2Al 2 O 3 ·5SiO 2 . Interest in these catalysts is a function of their good catalyst properties such as low gas dynamic resistance, mechanical strength, and thermal stability [6]. 3380040-5760/09/4505-0338We have already demonstrated the efficiency of catalytic compositions on a structurized support Cu-ZnO/Al 2 O 3 /cordierite for the partial oxidation of methanol (POM) [7,8]. The results obtained indicated that the key factor for obtaining good catalytic reaction parameters is the formation of highly active and selective Cu-ZnO microstructures on the catalyst surface, leading to a synergistic improvement in the indices of the POM reaction in comparison with samples prepared with either separate Cu or ZnO components.In...

Adsorption of Carbon Disulfide on Cu/CoSPc/Ce Modified Activated Carbon under Microtherm and Micro-oxygen Conditions

“…Further, the interaction between rare earth metals and transition metals can also be employed to improve catalyst capacity such as oxygen storage capacity and thermal stability. It was found that adding rare earth metals can prevent the growing of CuO or Cu 2 O grains under sintering conditions, , affording more even crystal size and pore size distribution. Meanwhile, because Cu and Ce ions possess distinctively different valences and radii, it is comparatively easier to form lattice defects and oxygen vacancies on the surface of the modified carbon material, which should improve the purification performance of adsorbent accordingly.…”