No abstract

Cylindrical internal reflectance infrared spectroscopy (CIR-FTIR) was used for the determination of the transport properties of hydrocarbons in zeolite L at high temperatures and pressures. This was the first time that the intracrystalline difisivity of hydrocarbons in microporous media could be determined under supercritical conditions by using a dynamic technique. The study investigated the self-difiion of n-heptane, the counterdifision of n-hexane and 1-hexene, and the codifSusion of n-heptane and pxylene in zeolite L under subcritical and supercritical conditions. The d i f i i o n time constants obtained for the single and binary systems showed that the diffusion within the pore was reduced significantly under supercritical conditions (i.e., liquidlike behauiod as the hydrocarbon density within the pore was increased.

Composite palladium membranes have extensively been studied in laboratories and, more recently, in small pilot industrial applications for the high temperature separation of hydrogen from reactant mixtures such as water‐gas shift (WGS) reaction or methane steam reforming (MSR). Composite Pd membrane fabrication methods have matured over the last decades, and the deposition of very thin films (1–5 µm) of Pd over porous ceramics or modified porous metal supports is quite common. The H 2 permeances and the selectivities achieved at 400–500 °C were in the order of 50–100 Nm 3 /m/h/bar 0.5 and greater than 1000, respectively. This chapter describes in detail composite Pd‐based membrane preparation methods, which consist of the grading of the support and the deposition of the dense metal layer, their performances, and their applications in catalytic membrane reactors (CMRs) at high temperatures (400–550 °C).