were used as supplied without further purification. The chemicals
used for the preparation of catalyst additives were NH4-ZSM-5 (CBV 5524G, Zeolyst, SiO2/Al2O3 = 50, Si/Al = 25), kaolin (Sigma-Aldrich), aluminum chloride hexahydrate (AlCl3·6H2O, Alfa Aesar, 99%) and LUDOX HS-40 (SiO2·xH2O, 40% SiO2, Sigma-Aldrich). OlefinsUltra
(Grace) was used as a reference material for catalytic tests. The
chemicals used for catalytic testing were 3-methylpentane (C6H14, Acros Organics, 99%) and n-hexane
(C6H14, VWR, ≥97%). Sample digestion
for subsequent elementary analysis by ICP-OES required hydrochloric
acid (HCl, VWR, 37%), nitric acid (HNO3, Carl Roth, 69%,
supra-quality), hydrofluoric acid (HF, Merck Millipore, 40%), and
boric acid (B(OH)3, Alfa Aesar, 99.99%).