Prem Kumar Seelam

Carbon supported catalysts in low temperature steam reforming of ethanol: study of catalyst performance

Three different metals (Pt, Pd and Ni) on multi-walled carbon nanotube and graphite supports were tested as catalysts in ethanol reforming experiments at low temperatures. The carbon nanotube based catalysts outperformed their counterparts supported on graphite in both ethanol conversion and hydrogen evolution. The palladium catalyst in both supports was rather inactive, whereas the nickel/nickel oxide catalyst showed excellent performance. The most active catalyst (Ni/CNT) showed ethanol conversion and hydrogen evolution already at 200 °C with complete conversion at 450 °C. The measured selectivity for H2 production was ∼42% with almost 100% conversion. Analysis of the spent catalyst samples revealed a considerable increase in carbon concentration caused by the formation of soot and coke on each sample but also carbon nanofibers and nanotubes were found to grow on the catalyst nanoparticles in the course of the steam reforming reactions.

Microreactors and membrane microreactors: fabrication and applications

Abstract: Process intensification (PI) is the future direction for the chemical and process industries and in this chapter, two key technologies to achieve this are discussed: microreactors and so-called membrane microreactors (MMRs). There is great potential to enhance the overall efficiency of microreactors by integrating them with membrane technologies to make mmRs and there are tremendous opportunities for the application of mmRs in many fields. This chapter reviews microreactor design, fabrication and applications as well as materials for micromembranes (MM). The integration of MMs with microreactors and the applications of the resulting mmRs are then discussed.

Advances in catalysts for membrane reactors

Abstract: Membrane reactors with a catalyst bed are designed to be used in various reactions, such as hydrogenation, dehydrogenation, oxidation and reforming reactions. The catalyst can be introduced into the reactor as a bed in several ways in the form, for example, of pellets, extrudates or tablets; or it can be incorporated in the reactor as a catalytic membrane wall. However, in many cases, the studies concentrate on the membrane itself, the development of catalysts is ignored, and commercial catalysts are used in the experiments. Most of the catalysts tested are aluminium oxide (alumina, Al 2 O 3 ) based, as alumina is a mature support and already well proven in convectional reactors. However, some new catalyst materials such as carbon nanotubes (CNTs), carbon black, gels and anodic aluminium oxide (AAO) are developed as innovative catalyst supports and catalysts, since there is also a need for new catalysts for membrane reactors.

Efficient Vapor-Phase Selective Hydrogenolysis of Bio-Levulinic Acid to γ-Valerolactone Using Cu Supported on Hydrotalcite Catalysts

Abstract In this work, Cu nanoparticles (Cu NPs, 2‐20 nm) supported on Hydrotalcite catalysts exhibit enhanced selectivity for γ‐valerolactone (GVL) during hydrogenolysis of levulinic acid (LA). At 260 °C, over 3 wt% Cu achieved 87.5% of LA conversion with a maximum GVL selectivity (95%). In contrast, LA hydrogenolysis over 3Cu/Hydrotalcite catalyst is highly active and stable toward the production of GVL due to balanced acido‐basicity and higher Cu dispersion with ultrasmall particle sizes, which are investigated through the temperature programmed desorption (TPD) of ammonia, N2O titration, and transmission electron microscopy (TEM) analysis. Hydrotalcite in combination with inexpensive Cu catalyst is found to be an efficient and environmentally benign for LA hydrogenolysis.

Low temperature steam reforming of ethanol over advanced carbon nanotube-based catalysts

Abstract Steam reforming of biofuels such as bioethanol offers a clean and sustainable route to improve hydrogen production capacity for the hydrogen economy. In this work, the influence of the carbon support type (carbon nanotube [CNT], activated carbon [AC] and graphitic carbon black [GCB]) and the addition of Pt (1 wt.%, 1.5 wt.% and 2 wt.%) and ZnO (10 wt.%) to Ni10/CNT (10 wt.% Ni) are studied in steam reforming of ethanol (SRE) at low temperatures (≤450°C). The prepared CNT-based catalysts were characterized by nitrogen physisorption, X-ray powder diffraction (XRD), energy-dispersive X-ray (EDX) and energy filtered transmission electron microscopy (EFTEM) analyses. Ni supported on CNTs was found to be highly active for SRE compared to other conventional carbon supported catalysts. The promotional effect of Pt in the Ni10Ptx/CNT catalysts was found to be unexpectedly insignificant in terms of ethanol conversion, hydrogen production and selectivity. By contrast, the hybrid (ZnO)10Ni10/CNT catalyst showed superior catalytic performance below 450°C with high H2 selectivity and low CO selectivity compared to all other CNT-based catalysts. The Ni10/CNT catalyst undergoes rapid deactivation compared to the ZnO promoted Ni10/CNT due to the large amounts of carbon deposition on the catalyst. The ZnO promoted Ni10/CNT catalyst enhances the hydrogen production and reduces the carbon formation, making the catalyst attractive for the SRE reaction.