DIRECT MASS-SPECTROMETRIC STUDIES OF THE DESTRUCTION OF HAZARDOUS WASTES .1. CATALYTIC STEAM RE-FORMING OF CHLORINATED HYDROCARBONS

Catalytic steam re-forming behavior was studied for a number of chlorinated and nonchlorinated organic species using the direct sampling capabilities of the molecular beam mass spectrometer (MBMS). Steam re-forming is an often used chemical process that can convert hydrocarbons into largely CO and H2. These screening studies investigated the possibility of using a catalytic steam re-forming environment to destroy hazardous waste by measuring destruction efficiencies and qualitatively comparing product slates with straight pyrolysis. For the steam re-forming, a rhodium catalyst on a reticulated alumina support was used and these observations were made. (1) Catalytic steam re-forming significantly enhanced the destruction of the compounds studied compared to destruction by pyrolysis. (2) Products of incomplete destruction are also significantly reduced, even for those species that are thermally stable. (3) Aromatics and acetonitrile are more difficult to steam re-form than aliphatic species. (4) A wide variety of species are susceptible to steam re-forming (including chlorine-containing species and acetonitrile) without any indication of catalyst deactivation over several 10-min periods. Two exceptions identified so far are the sulfur-containing species 3-methylthiophene and the phosphorus-containing species dimethyl methylphosphonate. Temperatures of the Rh catalyst must be maintained at 800-degrees-C or above to keep the catalyst active, at 50% steam in helium, for many compounds.