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In order to limit the increase in the global average temperature to 2 °C or below, the Paris Agreement proposed the reduction of CO 2 emissions throughout this century. Bioenergy with CO 2 capture and storage (BECCS) technologies represent an interesting option in order to allow this goal to be metgoal, because they are able to achieve negative CO 2 emissions. Chemical looping (CL) is recognized as one of the most innovative CO 2 capture technologies owing to its low energy penalty. CL processes permit the utilization of renewable fuels in a nitrogen-free atmosphere, given that the required oxygen is supplied by solid oxygen carriers. The present work presents an overview of the status of development of the use of biofuels in chemical looping technologies, including chemical looping combustion (CLC) and chemical looping with oxygen uncoupling (CLOU) for the production of heat/electricity, as well as chemical looping reforming (CLR), chemical looping gasification (CLG) and chemical looping coupled with water splitting (CLWS) for syngas/H 2 generation. The main milestones in the development of such processes are shown, and the future trends and opportunities for CL technology with biofuels are discussed.

Available online xxx Keywords:Hydrogen storage Adsorption Hydrothermal carbonisation KOH activation Microporous activated carbons a b s t r a c t 12 activated carbons (ACs) were prepared by KOH activation using hydrochars as precursors. These hydrochars were prepared by hydrothermal carbonisation (HTC) of sucrose solutions at concentrations ranging from 0.2 to 1.6 mol L À1 . The KOH to hydrochar weight ratio (W) was varied from 1 to 5, and the activation temperature was set to 1023 K. ACs texture was assessed by nitrogen and carbon dioxide adsorption at 77 and 273 K, respectively; pore size distribution was calculated by using both isotherms and the SAIEUS© software. ACs with surface areas between 790 and 2240 m 2 g À1 were obtained. Hydrogen excess adsorption was determined at 298 K and pressures up to 10 MPa in a volumetric device, and the isosteric heat of adsorption (Q st ) was calculated for four ACs, using hydrogen isotherms obtained at 278, 298 and 308 K. Potassium intercalation between graphitic planes was assumed to account for the high Q st values, 7e8 kJ mol À1 . Hydrogen uptake at 2 MPa was compared with hydrogen adsorption data of 38 other ACs reported in the open literature. Hydrogen adsorption fundamentally depends on micropore volume and preliminary HTC did not enhance hydrogen storage although it could be a good strategy for doping carbon with heteroelements.

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