Carbon dioxide is an iconic greenhouse gas and a major factor for current global climate changes, making essential its capture and recycling into valuable products and fuels.Methanol is a key compound that could be obtained from the 6-electrons, 6-protons CO2 reduction and that can be used both as a fuel and as a platform-molecule. The goal of this review is to present a comparative analysis of the CO2 reduction routes to methanol via heterogeneous and homogeneous catalytic hydrogenation, as well as enzymatic, photo-and electro-catalysis.After identifying catalytic materials and reaction conditions, we provide a comparative assessment of their respective advantages and drawbacks in terms of selectivity, productivity, stability, operating conditions, cost and technical readiness level. Currently, heterogeneous hydrogenation catalysis and electrocatalysis have the highest potential for the CO2 reduction to methanol at larger scale. Availability and price of sustainable electricity appear as essential prerequisites for efficient methanol synthesis from CO2.

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The Fe/olivine catalyst effectiveness regarding tar primary reduction during biomass gasification in dual fluidized beds has been investigated. The use of Fe/olivine instead olivine leads to an important decrease in the amount of produced tar, which was reduced by up to 65% at 850ºC, naphthalene being the most stable molecule. It has been found that Fe/olivine materials have a double effect on tar destruction. On the one hand, they act as a catalyst for tar and hydrocarbon reforming. On the other hand, they can act as an oxygen carrier that transfers oxygen from the combustor to the gasifier, and part of the oxygen is used to burn volatile compounds. The catalyst was fairly stable because the result was confirmed during 48 hours of continuous operation. The Fe/olivine material characterization (X-Ray Diffraction, Mössbauer spectroscopy, Temperature Programmed Reduction and Oxidation, etc.) revealed that the catalyst structure was maintained despite the large number of oxidizing-reducing cycles. The carbon that formed on the catalyst surface was low and easily oxidized in the combustion zone. Therefore, the inexpensive and non toxic Fe/olivine catalyst is a material suitable for use as primary catalyst in a fluidized bed gasification of biomass.

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In silica supported iron Fischer–Tropsch catalysts, promotion with copper strongly enhances both hematite reduction and magnetite carbidisation, while potassium promotion hinders reduction of hematite to magnetite but enhances magnetite carbidisation in carbon monoxide.

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In this work, 29 elements (Li, K,