Uptake of acetylene on cosmic dust and production of benzene in Titan's atmosphere

•Cyclo-trimerization of acetylene to benzene observed on cosmic dust mimics•Rates of acetylene uptake and cyclo-trimerization on dust measured•Surface area of Kuiper Belt dust particles in Titan's atmosphere modelled•Heterogeneous production of benzene between 80 and 120km is significant A low-temperature flow tube and ultra-high vacuum apparatus were used to explore the uptake and heterogeneous chemistry of acetylene (C2H2) on cosmic dust analogues over the temperature range encountered in Titan's atmosphere below 600km. The uptake coefficient, γ, was measured at 181K to be (1.6±0.4)×10-4, (1.9±0.4)×10−4 and (1.5±0.4)×10−4 for the uptake of C2H2 on Mg2SiO4, MgFeSiO4 and Fe2SiO4, respectively, indicating that γ is independent of Mg or Fe active sites. The uptake of C2H2 was also measured on SiO2 and SiC as analogues for meteoric smoke particles in Titan's atmosphere, but was found to be below the detection limit (γ