A new catalyst system for high-temperature solar reforming of methane

A new type of solar-heated reformer, called the volumetric reformer, has been recently developed. In this reformer, the concentrated solar radiation directly illuminates the catalyst through a transparent window. This new type of solar reformer can operate at a temperature range of 1273-1373 K, higher than that common in industrial reformers. Different configurations of the catalyst substrate in these volumetric reformers have been reported in the literature. This article describes a catalytic system specifically applied in the directly irradiated annular pressurized receiver (DIAPR), which was developed at the Weizmann Institute of Science for operation at high temperatures and pressures. The catalytic system based on the DIAPR concept was constructed on an array of ceramic pins loaded with catalyst. Cost-effective catalytic elements that will be implemented in this type of volumetric reformer were developed in the present work. A Ru/Al2O3 catalyst promoted with Mn oxides was supported on ceramic pins (made of alumina) by wash coating. The catalyst was characterized by SEM, XRD, and BET. The fresh catalyst contains mainly alpha-alumina and Mn2O3. Al2O3, Mn3O4, and MnAl2O4 were observed in the XRD pattern after reaction in the temperature range of 773-1473 K. Activity tests were conducted in a tube flow reactor made of sintered alumina (99.7% Al2O3). The results show that the activity of the new catalyst is similar to the activity of the commercial Engelhard 1%Ru/gamma-Al2O3 catalyst. However, while the activity of the commercial catalyst decreases drastically when approaching to 1273 K because of phase transformation in the support, the new catalyst is stable even after calcinations at 1373 K for 500 h under argon flow.