Conditions for HCN synthesis and catalyst activation over Pt-Rh gauzes

We have examined different processing conditions for the synthesis of HCN b y the ammoxidation of methane over woven Pt-Ph gauzes in an autothermal ben ch scale reactor. Compared to the conventional air processes, the HCN yield can be improved 10-15% by preheating the reactant gases, and HCN throughpu t can be increased 140% by removing N-2 from the feed stream. We were able to attain operation in a high pressure bench scale reactor, and HCN yields were maintained above 0.60 up to 3.5 atm at 300% of the throughput achievab le at 1 atm. We also investigated activation of the Pt-Ph gauze catalyst which occurs th rough facet and pit formation on the metal surface. A high temperature trea tment reduced activation times from 30 to 3 h. Pits on the catalyst surface resulted from increased temperatures and NH3 in the reactant gas, but HCN processing conditions were necessary for the catalyst to achieve best perfo rmance. (C) 1999 Elsevier Science B.V. All rights reserved.