Hydrocarbon conversion process

A hydrocarbon conversion process, comprising:

• (a) providing a first mixture comprising ≥90 wt. % of hydrocarbon having a hydrogen content in the range of from 6 wt. % to 25 wt. % and ≥4.0 ppmw mercaptan based on the weight of the first mixture;
• and
• (b) adding carbon monoxide to the first mixture and then pyrolysing the first mixture in a first region under pyrolysis conditions which include exposing the first mixture to a temperature≥1.20×103° C., to convert at least a portion of the first mixture's hydrocarbon and ≥90.0 wt. % of the first mixture's mercaptan based on the weight of mercaptan in the first mixture to produce a second mixture, the second mixture comprising ≥1.0 wt. % C2 unsaturates comprising acetylene, ≤20.0 wt. % CO and CO2 combined, ≤1.0 ppmw mercaptan, ≤1.0 ppmw thiophene based on the weight of the second mixture, wherein a molar ratio of CO to acetylene in the second mixture is in the range of from 0.005 to 0.2, and wherein the carbon monoxide is added in an amount up to and including 20 wt. % based on the weight of the second mixture.