Conception of Nanosized Membrane Reactors for Hydrogenation with Accumulated Hydrogen

Abstract

Results are summarized from studies to develop the concept of next-generation nanosized membrane reactors (NMRs) in which hydrogenation reactions are run in pores of varying diameter using hydrogen preadsorbed in mono- and multilayer oriented carbon nanotubes with graphene walls (OCNTGs) formed on the inner surface of pores of ceramic membranes. A comparative analysis is performed of the morphology of such carbon nanostructures as graphenes, OCNTGs, and pyrocarbon nanocrystallites (PNCs), and morphology is studied via X-ray diffraction analysis, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and transmission electron microscopy (TEM). It is shown that only OCNTGs are capable of accumulating and storing hydrogen. The mechanism of hydrogen adsorption and the laws governing adsorption in this nanostructure are discussed. Results from the noncatalytic hydrogenation of decene-1 and naphthalene in NMRs with hydrogen adsorbed in OCNTGs are analyzed, and the kinetics and activation energies for these reactions are determined. The effect of the substrate on which graphene nanostructures are synthesized is estimated through a comparative analysis of the mechanisms of hydrogen adsorption in OCNTGs and cylindrical and planar graphene nanostructures (CPGNSes) formed on zeolites. The concept of NRMs is formulated, the directions of developing the concept are discussed. These include devising ways to create of catalytically active metal-containing sites in the NMR structure and the effect of the steric factor of the nanoreactor configuration on the selective hydrogenation of different organic substrates.