Modern Trends in Design of Catalysts for Transformation of Biofuels into Syngas and Hydrogen: From Fundamental Bases to Performance in Real Feeds

Abstract

This review considers problems related to design of efficient structured catalysts for natural gas and biofuels transformation into syngas. Their active components are comprised of fluorite, perovskite and spinel oxides or their nanocomposites (both bulk and supported on high surface area Mg-doped alumina or MgAl2O4) promoted by platinum group metals, nickel and their alloys. A complex of modern structural, spectroscopic and kinetic methods was applied to elucidate atomic-scale factors controlling their performance and stability to coking, such as dispersion of metals/alloys, strong metal-support interaction and oxygen mobility/reactivity as dependent upon their composition and synthesis procedures. Monolithic catalysts comprised of optimized active components loaded on structured substrates with a high thermal conductivity demonstrated high activity and stability to coking in processes of natural gas and biofuels reforming into syngas. A pilot-scale axial reactor equipped with the internal heat exchanger and such catalysts allowed to efficiently convert into syngas the mixture of natural gas, air and liquid biofuels in the autothermal reforming mode at low (~50–100 °C) inlet temperatures and GHSV up to 40,000 h−1.

Approaches to the design of efficient and stable catalysts for biofuel reforming into syngas: doping the mesoporous MgAl2O4 support with transition metal cations

“…14 The effective diffusion coefficient for this oxygen is nearly the same for all catalysts (∼5 × 10 −14 cm 2 s −1 at 700 K) with an apparent activation energy of ∼100 kJ mol −1 . This is approximately an order of magnitude lower value of D at this temperature as compared with that for Ni-doped Pr–Ce–Zr–O oxide (3 × 10 −13 cm 2 s −1 ), 39 which is apparently explained by the interaction of supported fluorite-oxide with MgAl 2 O 4 and incorporation of Mg and Al cations into its lattice. Nevertheless, it is still sufficiently high to prevent catalyst coking through fast oxygen diffusion from fluorite to the boundary with Ni–Ru alloy nanoparticles.…”

“…Interest towards these reactions is caused by the possibility to tune the H 2 /CO ratio in the syngas as well as to provide the autothermal mode of operation with the addition of oxygen to the feed. 39 In these reactions the stable performance at ∼750 °C and contact times of 0.25-0.35 s was demonstrated as well (Fig. S15 and S16 †).…”

“…Nevertheless, it is still sufficiently high to prevent catalyst coking through fast oxygen diffusion from fluorite to the boundary with Ni–Ru alloy nanoparticles. 39…”

“…Nevertheless, it is still sufficiently high to prevent catalyst coking through fast oxygen diffusion from fluorite to the boundary with Ni-Ru alloy nanoparticles. 39 Table 3 The concentration of various surface sites estimated from the FTIR spectra of CO at −196 °C and pCO 10 Torr Paper Dalton Transactions…”