TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Method: The method includes quenching the reactive hydrocarbon products, and preparing acetylene-rich liquefaction feed from the quenched hydrocarbon products by intermediate processing.The intermediate processing includes separating effluent stream(s) comprising non-acetylene component, e.g. carbon dioxide, hydrogen, carbon monoxide, light gases, syngas, and/or ethylene, from the quenched hydrocarbon products; separating a light-gas-rich stream from the quenched hydrocarbon products; hydrogenating the acetylene-rich liquefaction feed; and recycling effluent stream to the conversion reactor.The intermediate processing may include separating a carbon-dioxide-rich effluent stream, a hydrogen-rich effluent stream, a syngas-rich effluent stream, and a light-gas-rich stream from the quenched hydrocarbon products; and hydrogenating the acetylene rich liquefaction feed.The hydrogen-containing effluent stream may be conveyed to an electrical power generation device, and electrical power is generated from the hydrogen and an oxygen-containing stream.Portion(s) of natural gas that is converted to reactive hydrocarbon products is heated with the generated electrical power. Portion(s) of natural gas that is converted to reactive hydrocarbon products may be heated by products of combustion of a second portion of natural gas with an oxidant.The method also includes separating a product stream from the catalytic liquefaction reactor into a liquid product stream comprising the hydrocarbon liquids and a gas stream, recycling the gas stream to the conversion reactor, and recovering the liquid product stream. In other embodiment, converting natural gas to hydrocarbon liquids includes providing a natural gas stream; providing a feed stream comprising all or part of the natural gas stream; providing a burn stream comprising combustible material; conveying the feed stream and burn stream to a reactor, where the burn stream is combusted with an oxidant and the feed stream is heated by intimate mixing with the combustion products to predetermined temperature for sufficient time to form a product stream comprising reactive products and hydrogen; quenching the product stream; passing portion(s) of the product stream to a catalytic liquefaction reactor; and producing the hydrocarbon liquids in the catalytic liquefaction reactor.Contaminants are removed from the natural gas stream. The oxidant is preheated to 400-1800 K.The natural gas stream and/or oxidant are preheated by electric arc, resistance heater, plasma generator, fuel cell, combustion heater, and/or heat exchanger.The feed stream is preheated to 400-1800 K and maintained at at least 400 K for 0.1-100 (preferably 0.2-10) milliseconds.The burn stream is preheated to 400-1800 K.A portion of feed stream is converted to reactive products comprising acetylene and/or ethylene by pyrolysis, partial oxidation, combustion, oxidative coupling, electric arc, resistance heater, plasma generator, and/or catalytic conversion.Portion(s) of reactive products may be reacted with hydrogen to form ethylene.The product stream is quenched using a Joule-Thompson expander, nozzle, turbo expander, water spray, hydrocarbon spray, oil spray, steam, boiler, and/or heat exchanger.The product stream is quenched by mixing the product stream with vapor or liquid hydrocarbons.Portion(s) of the product stream is passed to a separator to remove some carbon dioxide and some hydrogen.Portion(s) of hydrogen is passed to the reactor so that the burn stream comprises the removed hydrogen. Water and/or steam are introduced into the reactor. Nitrogen may be introduced into the reactor.The nitrogen is heated by electric arc, resistance heater, plasma generator, fuel cell, combustion heater, and/or heat exchanger prior to its introduction to the reactor. Hydrogen is conveyed to a fuel cell or turbine, oxygen is provided to the fuel cell or turbine, and hydrogen is reacted with oxygen in the fuel cell or is burned with the oxygen in the turbine to produce electricity.The fuel cell or turbine produces heat and water.The water is heated to form steam, and electricity is generated from the steam.Preferred Parameters: The pressure of natural gas stream is 1-20 bar. The catalytic liquefaction reactor is operated at 300-1000 K.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The feed stream comprises light hydrocarbons, e.g. methane, ethane, propane, butane, and/or isobutane.The burn stream comprises a portion of natural gas stream. The reactive hydrocarbon products comprise ethylene.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The oxidant comprises oxygen supplied from a source, e.g. oxygen, purified oxygen, air, or oxygen-enriched air.    TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Apparatus: The conversion reactor is a non-catalytic reactor or a mixed-stream reactor. The catalytic liquefaction reactor comprises an acid catalyst.