TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: In the process, each microchannel distillation section comprises at least one process microchannel and an adjacent liquid channel comprising a wicking region; part of the wicking region forms a wall of the process microchannel, where the liquid phase flows in the wicking region and the vapor phase flows in the process microchannel and contacts the liquid phase. A heat exchange fluid flows through the heat exchange channel co-current, cross-current or counter-current relative to its first direction. The gauge pressure within the microchannel distillation sections is in the range of 30-100 atmospheres, and a heat exchange fluid flows in the heat exchange channel, where the temperature of the heat exchange fluid is -30 to 200degreesC. The heat exchange fluid undergoes a phase change in the heat exchange channel or partial boiling in the heat exchange channel. The flow of the liquid phase is driven by gravitational forces and/or a pressure differential. The more volatile component rich vapor phase is condensed in a microchannel condenser. The less volatile component rich liquid phase is vaporized and flows into the process microchannel. In the process of separating ethylene from a fluid mixture, the distillation unit has a height of up to about 3 meters; the ethylene enriched vapor phase has an ethylene content of at least about 99 vol.%. In the process of distilling a fluid mixture in a distillation apparatus, the distillation process is conducted in all of the microchannel distillation units in the distillation apparatus or conducted in some but not all of the microchannel distillation units in the distillation apparatus.Preferred Materials: The heat exchange fluid comprises one or more of air, steam, liquid water, carbon dioxide, gaseous nitrogen, liquid nitrogen, a gaseous hydrocarbon or a liquid hydrocarbon.Preferred Components: The process microchannel comprises a liquid inlet, a liquid outlet, an interior wall extending from the liquid entrance to the liquid exit, and a capture structure, the liquid outlet being downstream from the liquid inlet. The liquid phase flows along the surface of the interior wall, the liquid phase being in the form of a thin film. The process microchannel has an internal dimension of width or height of up to about 10 (preferably 2) mm. The process microchannel is made of a material comprising steel, monel, inconel, aluminum, titanium, nickel, copper, brass, an alloy of any of the metals, a polymer, ceramics, glass, a composite comprising a polymer and fiberglass, quartz, silicon, silicon carbide, boron carbide, metal carbide, silicon nitride, boron nitride and/or metal nitride. The liquid channel has an internal dimension of width or height of up to about 10 (preferably 2) mm. The heat exchanger comprises at least one heat exchange channel having an internal dimension of width or height of up to about 10 (preferably 2) mm. The capture structure comprises wire mesh, one or more of inverted cones, liquid-nonwetting porous structure, liquid-wetting porous structure, perforated foil and fibers. The wicking region comprises a wick comprising one or more of sintered metal, metal screen, metal foam or polymer fibers; a wicking surface comprising grooves in one or more interior walls of the liquid channel, where the grooves are aligned parallel to the direction of flow of the vapor phase in the process microchannel; and the grooves are aligned tangentially to the direction of flow of the vapor phase in the process microchannel. The grooves provide a flow path for the liquid phase to the another microchannel distillation section. The heat exchanger comprises at least one heat exchange channel and an endothermic or exothermic process is conducted in the heat exchange channel. The exothermic process comprises a water-gas shift reaction, a methanol synthesis reaction or an ammonia synthesis reaction, while the endothermic reaction comprises a steam reforming process or dehydrogenation process. The microchannel distillation sections have adjacent heat exchange channel zones, a heat exchange fluid flows in the heat exchange channel zones, the heat exchange fluid undergoing partial boiling in the heat exchange channel zones, the pressure of the heat exchange fluid in each of the heat exchange channel zones being different and the temperature in each microchannel distillation section being different. The microchannel distillation unit further comprises a microchannel condenser for condensing vapor and a microchannel reboiler for vaporizing liquid. In the microchannel distillation unit, the supplemental vapor inlet being suitable for permitting vapor to flow from the first supplemental vapor channel into the microchannel distillation section, the second supplemental vapor channel and the supplemental vapor outlet being suitable for permitting vapor to flow from the microchannel distillation section to second supplemental vapor channel; the microchannel distillation unit is formed using sheets of material with portions removed that allow flow passage; the microchannel distillation unit is formed using a stack of sheets to form an integrated microchannel distillation unit; the microchannel distillation unit is assembled using a combination of sheets and partial sheets. The heat exchanger comprises an electric heating element, resistance heater and/or non-fluid cooling element.