Abstract: Selective recovery of C2 to C4 hydrocarbons is achieved through the use of a converging-diverging nozzle, or de Laval nozzle. The vapor stream comprising C2 to C4 hydrocarbons is fed into an inlet of a de Laval nozzle having a throat. The vapor stream may have an initial temperature of between 0° C. and 100° C., and an initial pressure of between 200 psig and 500 psig. In the de Laval nozzle, the vapor stream expands after passing through the throat of the de Laval nozzle, producing a vapor stream having reduced temperature and pressure. Then, C2 to C4 hydrocarbons condense from the reduced-temperature vapor stream as liquid droplets, which may be recovered. Fractionation of C2 to C4 hydrocarbons by means of a de Laval nozzle is possible; the technique allows selective recovery of propane from a mixture of propane and ethane.

Abstract: Disclosed is a method for forming enals from corresponding alehydes in a single enclosed unit such as a divided wall reaction distillation unit. The method of the present invention includes (a) feeding an aldehyde feed stream comprising at least one aldehyde reactant into a reaction zone contained within said single enclosed unit; (b) reacting said at least one aldehyde reactant in said reaction zone in the presence of a catalyst to form an enal-containing reaction zone effluent comprising an enal; (c) purifying said enal-containing reaction zone effluent in a first separation zone within said single enclosed unit to form an enal-rich product mixture and a residual unreacted aldehyde mixture; and (d) collecting from said single enclosed unit at least a portion of said enal-rich product mixture. The method of the present invention results in high enal yields at a markedly reduced capital cost and energy consumption as compared to prior art processes.