Downstream catalytic stabilization and selective recycle system for plasma reactor effluents

A system, comprising:

• a plasma reactor configured to receive a feed gas flow at an inlet of the plasma reactor and to produce a mixture of saturated and unsaturated hydrocarbons and hydrogen;
• a catalyst bed disposed downstream of the plasma reactor, wherein the catalyst bed is configured to hydrogenate the unsaturated hydrocarbons from the plasma reactor and yield a product flow;
• a separator configured to receive the product flow from the catalyst bed and separate the product flow into liquid products, excess hydrogen for collection, and recycle gas, wherein the separator comprises a low-pressure vessel operable at or near pressure conditions of the plasma reactor;
• and
• a recycle system configured to direct the recycle gas to the inlet of the plasma reactor, the recycle system comprising a hydrogen to hydrocarbon (H2/HC) controller configured to:
• determine a H2/HC ratio of gas fed to the plasma reactor based on a number of moles of hydrogen in the recycle gas per mole of the feed gas flow;
• and
• control a flow of the recycle gas to the inlet of the plasma reactor to maintain the H2/HC ratio within a target range without external hydrogen being added to the recycle gas, wherein the target range of the H2/HC ratio is set to enhance both plasma conversion of the feed gas flow and hydrogenation efficiency of the unsaturated hydrocarbons and to provide process stability to the catalyst bed.