Contents lists available at ScienceDirect Journal of CO 2 Utilization journal homepage: www.elsevier.com/locate/jcou Selective CO 2 hydrogenation into methanol in a supercritical flow process Maitê L. Gothe a , Fernando J. Pérez-Sanz a , Adriano H. Braga a , Laís R. Borges a , Thiago F. Abreu b , Reinaldo C. Bazito a , Renato V. Gonçalves c , Liane M. Rossi a , Pedro Vidinha a, * a Institute of Chemistry, University of São Paulo, Av Professor Lineu Prestes, 748, São Paulo, SP, Brazil b Chemical Engineering Department, Polytechnic School, University of São Paulo, Av. Prof. Lineu Prestes, 580, São Paulo, SP, Brazil c São Carlos Institute of Physics, University of São Paulo, Av João Dagnone, 1100, São Carlos, SP, Brazil ARTICLE INFO Keywords: CO 2 Carbon dioxide Hydrogenation Methanol Supercritical fluids Flow process Rhenium Nanoparticles ABSTRACT Methanol plays a crucial role in the novel cycle of carbon capture, recycling and valorisation of anthropogenic carbon dioxide (CO 2 ). Even though hydrogenation of CO 2 to methanol has favourable thermodynamics, catalyst and processes development is needed for improving stability, reaction rate and selectivity to higher values than of the currently used copper oxide on zinc oxide (CuO/ZnO) catalysts. Here we report an efficient supercritical flow process for the selective valorisation of CO 2 into methanol. At optimized conditions, rhenium oxide on titanium dioxide (ReO x /TiO 2 ) catalyst converts CO 2 into methanol with 98% selectivity and at 18% CO 2 con- version rate at 200 °C, 100 bar and CO 2 /H 2 ratio of 1/4. A higher conversion of 41% can be achieved at 250 °C, but the selectivity towards methanol decreases to 64%. This strategy has enabled the development of an efficient high-pressure flow process without compromising methanol selectivity. 1. Introduction The global warming as a result of anthropogenic emissions of CO 2 is by far the greatest challenge of mankind. In 2018, emissions of carbon dioxide from anthropic sources of combustion reached the historic value of 33.1 GtCO 2 [1]. At this point, without efficient abatement measures and actions, the goals established by the Paris agreement [2] will be virtually impossible to attain. Therefore, a variety of efforts has been placed into developing economically feasible strategies to enable the capture of CO 2 . This concept can be achieved by following two main strategies: Carbon Capture and Sequestration (CCS) or Carbon Capture Utilization (CCU). The latter is a rather novel concept of carbon foot- print reduction and it is based on converting carbon dioxide into fuel or valuable chemicals. Several strategies have been proposed to accom- plish this. They can be chemical, electrochemical, photochemical or biochemical catalytic processes [3–11]. A myriad of products can be obtained from CO 2 such as organic or inorganic carbonates, amides, urea, salicylic acid, syngas, fuel hydrocarbons or fuel alcohols [12]. Despite the numerous catalytic concepts developed for the valor- isation of CO 2 , heterogeneous catalysis has been one of the most studied strategies for that purpose, especially due to the industrial know-how of operation and scale-up of such catalytic processes. Methanol (CH 3 OH) is considered one of the most promising platform molecules obtainable directly from CO 2 , since it can be integrated in numerous upgrading processes, making a closed carbon cycle economy possible [13]. The direct substitution of petroleum based fuels by methanol in internal combustion engines has also been shown to be feasible [14,15]. Moreover, unlike CO 2 derived methanol, the use of fossil fuels causes urban air pollution, which leads to an increase in the occurrence of respiratory diseases and deaths from cardiovascular and respiratory ailments due to alveolar inflammation, as demonstrated by epidemio- logical studies [16]. Hence, a methanol economy can aid the im- provement of urban pollution and public health, as well as help miti- gating the greenhouse effect, if it is derived from CO 2 . Methanol consumption and demand has been growing intensely worldwide, and that growing trend is even more evident in China, where the govern- ment has set goals to tackle air pollution [17]. In light of this context, methanol as fuel or platform molecule is rising as one of the most promising energetic transition solutions. Therefore, the development of novel catalytic materials can be focused on accomplishing the clean and selective production of methanol from CO 2 . So far, the only large-scale process of CO 2 conversion into methanol is the Vulcanol® process, de- veloped by Carbon Recycling International at the George Olah plant in Iceland. This process uses copper oxide (CuO), zinc oxide (ZnO) and/or aluminium oxide (Al 2 O 3 ) as heterogeneous catalysts [18]. Various studies have been performed in order to improve the ac- tivity of the CuO/ZnO catalysts by modifying or combining the oxides used to support Cu. In one example, a zirconium dioxide (ZrO 2 ) support https://doi.org/10.1016/j.jcou.2020.101195 Received 17 January 2020; Received in revised form 16 May 2020; Accepted 16 May 2020 ⁎ Corresponding author. E-mail address: pvidinha@iq.usp.br (P. Vidinha). Journal of CO₂ Utilization 40 (2020) 101195 Available online 04 June 2020 2212-9820/ © 2020 Elsevier Ltd. All rights reserved. T