An isotopic study of the transhydrogenation of propyne with propane over a potassium-doped chromia/alumina catalyst

The transhydrogenation of propyne and propane to propene was studied over a potassium-doped chromia/alumina catalyst over the temperature range 773-873 K. In the absence of propane, propyne further reduced the catalyst and produced carbon deposits and methane. Only trace quantities of propene were observed. As expected propane in the absence of propyne underwent dehydrogenation to from propene close to thermodynamic limitations. The transhydrogenation reaction was shown to require full dehydrogenation of propane to propene by use of isotopic labels. Transhydrogenation was observed at 823 and 873 K. By 873 K, the conversion to propene was such that 80% of the C-3 stream was propene. However, the yield of propene was low due to secondary reaction leading to methane and carbon.