Open flow hot isostatic pressing assisted synthesis of unsupported MoS2 catalysts Original Research Article

We report the development and application of a new technique for synthesizing highly porous unsupported catalytic materials. The new technique is called open-flow hot isostatic pressing (OFHIP) technique. In this technique, an isostatic pressure is first applied to the catalyst precursor in an open flow fashion, and then heat is applied. Under this condition, as the organic components gradually decompose and leave the material, the voids left behind are immediately filled by the gas (pressure medium) in flow. This substitution warrants the preservation as well as the uniformity of the voids/pores. The result is a very porous material with uniform pore size distribution.The general goal was to determine the optimal conditions of temperature and pressure for best catalytic activity results. Results indicated that besides temperature and pressure, the catalyst precursor had significant effects, as well. The unpromoted MoS2 samples synthesized at 300 °C indicate that as the synthesis pressure increased, both surface area and catalytic activity of the materials produced increased. The catalytic activity k value increased by a factor of 2 from 3 to 6 × 10−7 mol/g s that corresponds to increase in pressure from 100 to 800 psi (6.9 to 55.2 bar), respectively. The N2 gas used as pressure medium resulted in highly porous materials but low activity. H2 appeared to be the ideal gas for both pressure medium and reducing agent. Co-promoted MoS2 catalysts synthesized at 1400 psi (96.5 bar) and 300 °C showed catalytic activity as high as 37 mol/g s.