2.1 Chemicals
If not specified, the chemicals were of analytic grade. Benzene, cyclohexene (A.R.), acetic acid (A.R.), Cu(NO3)2โ‹…3H2O, Zn(NO3)2โ‹…6H2O, Na2SiO3ยท9H2O, and NaOH were purchased from Sinopharm Chemical Reagent. Amberlyst 15 and La(NO3)3โ‹…6H2O were purchased from J&K. The gases were purchased from Beijing Haipu Gas.