Continuous production of thiophene from butane

In a continuous catalytic gas-phase process of reacting hydrogen sulfide with one or more C.sub.4 hydrocarbons selected from the group consisting of normal butane, normal butenes and mixtures thereof to produce thiophene, by-product carbon disulfide and by-product hydrogen comprising

• continuously preheating the said C.sub.4 hydrocarbon reactant within the range 500.degree. to 900.degree.F. and separately preheating the hydrogen sulfide reactant within the range of 900.degree. to 1100.degree.F. and
• thereafter introducing the said reactant gases to a dehydrogenation catalytic reactor maintained at a temperature within the range of 900.degree. to 1100.degree.F.
• continuously withdrawing a product stream from the said reactor containing thiophene, carbon disulfide, hydrogen, excess hydrogen sulfide and unreacted C.sub.4 hydrocarbons, separating thiophene and carbon disulfide from the reactor product stream while recycling excess hydrogen sulfide and unreacted C.sub.4 hydrocarbons to the said reactor and regenerating the dehydrogenation catalyst when the conversion to thiophene falls off,
• the improvement consisting of introducing the said reactant gases at a mole ratio of hydrogen sulfide to C.sub.4 hydrocarbon ranging from about 15 to 1 to about 20 to 1 to an adiabatic reactor containinng a dehydrogenation catalyst while
• simultaneously introducing sulfur vapor to the catalyst to react with by-product hydrogen and thereby to generate heat in an amount sufficient to maintain the catalyst temperature within the range of 900.degree. to 1100.degree.F.