Lanthanum doping for longevity of alumina catalyst bed in hydrogen peroxide thruster

Abstract

The effects of doping alumina catalyst supports with lanthanum were investigated in terms of catalyst performance in a high concentration hydrogen peroxide monopropellant thruster. The catalyst support was doped with lanthanum by wet impregnation method in different conditions and characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and bulk crushing strength (BCS) test. XRD showed adequate crystal structure by doping lanthanum on alumina and BET analysis demonstrated that the reduction of active surface area was modest, even though the catalyst was cured at a temperature higher than the phase transition temperature of alumina. The BCS test exhibited a 57.75% increase in the mechanical strength of the lanthanum doped alumina compared to pure gamma-alumina. A 50 N monopropellant thruster was built and firing tests were conducted to examine the longevity of manganese oxide lanthanum doped alumina catalyst. The catalyst pellets were removed from the thruster and analyzed. The experimental results have shown significant improvements in the longevity of the catalyst. The firing tests have shown significant improvement in catalyst volume loss, along with characteristic velocity efficiency higher than 98%. The catalyst with lanthanum doped alumina has also shown better pressure stability and a steady pressure drop across the catalyst bed.