Lorenzo Spadaro

Latest Advances in the Catalytic Hydrogenation of Carbon Dioxide to Methanol/Dimethylether

Huge releases and continuous rise of CO2 levels in the atmosphere represent one of the most critical environmental issues of the twenty-first century, deserving novel energetic, economic and sociological policies to prevent more severe consequences of the ongoing global warming on climate and future of the Earth. This imposes urgent measures for a major cut of CO2 emissions by an extensive recycle to valuable chemicals and fuels, like methanol (MOH) and dimethylether (DME). CO2-hydrogenation processes are also expected to play a major positive impact on current MOH economy, allowing syngas manufacture from natural gas streams containing large CO2 percentages or by methane oxy-reforming instead of the energy-intensive steam reforming technology. In this context, this chapter presents the latest advances concerning the catalytic aspects and the novel engineering approaches for MOH–DME manufacture via CO2-hydrogenation processes.

Which Future Route in the Methanol Synthesis? Photocatalytic Reduction of CO 2 , the New Challenge in the Solar Energy Exploitation

Abstract Nowadays, the practical exploitation of the sun for industrial purposes is still almost limited to the photovoltaic and the solar-thermal technologies. As an alternative route, the direct photoconversion of CO 2 to methanol is potentially one of the most promising ways for a larger utilization of the solar source. Since the late 1970s, many studies have been proposed for reproducing artificially the photosynthesis process, aiming to convert CO 2 into high value products. Indeed, the direct photoconversion of CO 2 is energetically more effective than catalytic hydrogenation processes, although the energy density and the efficiency of the current photocatalytic systems are still far away from large scale application. Thus, advances in the photocatalytic CO 2 conversion deserve systematic efforts in the fields of material science and reactor engineering. To overcome this technological gap, two feasible routes are pursued; these consist in the development of efficient photocatalytic materials at higher “quantum yield” for improving activity and selectivity, and the optimization of the photoreactor configuration enhancing the light transmission over the photocatalytic phase.

A definitive assessment of the CO oxidation pattern of a nanocomposite MnCeOx catalyst

The CO oxidation pattern of a nanocomposite MnCeOx catalyst (M5C1; Mnat/Ceat, 5) in the range of 293–533 K (P, 1 atm) has been probed under a kinetic regime, varying reagent pressure (p0CO, 0.01–0.025 atm; λ0, 1), ratio (λ0, 0.25–4.0) and CO2 co-feeding (0.05–0.10 atm). Activity data indicate fractional orders on pCO (0.6 ± 0.1) and pO2 (0.4 ± 0.1), with an activation energy of 40 ± 3 kJ mol−1, and a negative kinetic effect of CO2 co-feeding due to competitive adsorption processes. Coupled with systematic evidence on the reactivity and mobility of catalyst oxygen and surface intermediates, kinetic data disclose a concerted redox mechanism of Langmuir–Hinshelwood type, which starts by abstraction of O-atoms from surface active MnIV centres (r.d.s.), and is sustained by adsorption of diatomic oxygen species on O-vacancies. The derivative and integral forms of the formal rate equation explain the empirical kinetics, predicting the activity pattern of the MnCeOx catalyst in the range of 293–533 K.