Pd Nanoparticles on the Outer Surface of Microporous Aluminosilicates for the Direct Alkylation of Benzenes using Alkanes

The direct alkylation of benzenes with simple alkanes is one of the ideal processes for the production of alkylbenzenes. We demonstrated that Pd nanoparticles on the outer surface of H-ZSM-5 are efficient catalysts for direct alkylation. The reaction proceeds through the activation of an alkane on the acid sites present inside the zeolite pores. This process is followed by the nucleophilic addition of an arene to activate the activated alkane. The spillover of the abstracted hydrogen atoms from the acid sites to the Pd nanoparticles on the outer surface accelerates recombination to H2. A maximum toluene conversion of 58.5% and a selectivity of 95.6% for the alkylated products are achieved when toluene is reacted with n-heptane. para-selective alkylation is achieved due to the effect of the pore size of H-ZSM-5. The μ+SR study of muonium, a pseudoisotope of hydrogen, in aluminosilicates suggested that the formation of atomic hydrogen is possible and its lifetime is in the submicrosecond range or longer, which is long enough for chemical reactions.