Zeolite catalysts have been evaluated for the gas-phase conversion of decane, to study new routes for upgrading intermediate-length straight chain hydrocarbons. For a gas-feed of dilute n-decane in an inert carrier, at a contact time of 4 s, the initial activity of ZSM-5 and Ga/ZSM-5 was consistently high (>95% conversion) over the temperature range 300–460 °C. The parent zeolite produced almost equal yields of cracked hydrocarbons and aromatics, while the Ga-modified zeolite produced predominantly BTX and other heavier aromatics. This difference in product distribution is consistent with the short-chain alkanes formed within the internal pore structure of the zeolite being intermediates in a Cyclar-type aromatisation mechanism, while the direct conversion of decane to heavy (C10–C15) aromatics occurs at the unconstrained external acid sites. Under aerobic conditions, the rate of CO formation was negligible and CO2 was barely detectable over either the parent or the Ga-modified zeolite, even though all the O2 was consumed. The ability of Ga/ZSM-5 to catalyse selective oxidation, of the H2 released during the dehydrogenation steps, thus provides the prospect of the aromatisation reaction being operated autothermally. Although the external sites are preferentially blocked by carbon retention, rapid deactivation did not occur until after 65 h on line (under either anaerobic or aerobic conditions) when blocking of the internal pore structure became limiting.

On-board autothermal reforming, which had been intended for mobile fuel cell applications, has evolved into exhaust gas reforming—a technology that could make it more difficult for the internal combustion engine to be displaced. Among the technical barriers that prevented implementation of fuel cell drivetrains based on autothermal reforming was the integration of several chemical processes into an energy- and space-efficient system with a high degree of heat management. By contrast, an exhaust gas reformer bears much more resemblance to the passive catalytic converters used for exhaust-gas after treatment, except that it is located in a recirculation loop close to the engine. When the reactions are predominantly endothermic, the reformer recovers waste heat and generates reformate with a higher fuel heating value than that of the fuel it consumes. The reformate does not need any further treatment, but can be fed directly to the engine, where it will have an additional impact on fuel economy by acting as a gas-phase combustion promoter. On-board reforming also increases the number of potential after treatment options, some of which are substantially improved by the addition of hydrogen.

Zeolite catalysts have been evaluated for the gas-phase conversion of decane, to study new routes for upgrading intermediate-length straight chain hydrocarbons. For a gas-feed of dilute n-decane in an inert carrier, at a contact time of 4 s, the initial activity of ZSM-5 and Ga/ZSM-5 was consistently high (>95% conversion) over the temperature range 300–460 °C. The parent zeolite produced almost equal yields of cracked hydrocarbons and aromatics, while the Ga-modified zeolite produced predominantly BTX and other heavier aromatics. This difference in product distribution is consistent with the short-chain alkanes formed within the internal pore structure of the zeolite being intermediates in a Cyclar-type aromatisation mechanism, while the direct conversion of decane to heavy (C10–C15) aromatics occurs at the unconstrained external acid sites. Under aerobic conditions, the rate of CO formation was negligible and CO2 was barely detectable over either the parent or the Ga-modified zeolite, even though all the O2 was consumed. The ability of Ga/ZSM-5 to catalyse selective oxidation, of the H2 released during the dehydrogenation steps, thus provides the prospect of the aromatisation reaction being operated autothermally. Although the external sites are preferentially blocked by carbon retention, rapid deactivation did not occur until after 65 h on line (under either anaerobic or aerobic conditions) when blocking of the internal pore structure became limiting.