Citation: Hosseinzaei, B.; Hadianfard, M.J.; Esmaeilzadeh, F.; Recio-Ruiz, M.d.C.; Ruiz-Rosas, R.; Rosas, J.M.; Rodríguez-Mirasol, J.; Cordero, T. Assessment of Agricultural Residue to Produce Activated Carbon-Supported Nickel Catalysts and Hydrogen Rich Gas. Catalysts 2023, 13, 854. https:// doi.org/10.3390/catal13050854 Academic Editors: M. A. Alvarez- Montero and Luisa Maria Gomez-Sainero Received: 26 March 2023 Revised: 22 April 2023 Accepted: 6 May 2023 Published: 8 May 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). catalysts Article Assessment of Agricultural Residue to Produce Activated Carbon-Supported Nickel Catalysts and Hydrogen Rich Gas Behnam Hosseinzaei 1 , Mohammad Jafar Hadianfard 1, * , Feridun Esmaeilzadeh 2 , María del Carmen Recio-Ruiz 3 , Ramiro Ruiz-Rosas 3, * , Juana M. Rosas 3 , José Rodríguez-Mirasol 3 and Tomás Cordero 3 1 Department of Material Science and Engineering, School of Engineering, Shiraz University, Shiraz 71348, Iran; hosseinzaei1991@gmail.com 2 Department of Chemical and Petroleum Engineering, School of Chemical and Petroleum Engineering, Shiraz University, Shiraz 71345, Iran 3 Departamento de Ingeniería Química, Campus de Teatinos s/n, Universidad de Málaga, Andalucía Tech., 29010 Málaga, Spain * Correspondence: hadianfa@shirazu.ac.ir (M.J.H.); ramiro@uma.es (R.R.-R.) Abstract: The aim of this study was to synthesize chemically activated carbons from different agricultural residues, i.e., pistachio shell (PS), bitter orange peel (OP), and saffron petal (SP), and subsequently to use them as supports for loading a Ni catalyst. Supercritical water gasification of bio- oil was applied to investigate the catalytic performance of the resulting catalysts. The physicochemical properties of the activated carbon (ACs) and the catalysts (Ni/ACs) were characterized with BET, XRD, XPS, TEM, and TPD. The adsorption results showed that the ACs developed considerable pore structures, containing both micro- and mesopores, which was validated by the well-distributed active phases on the supports in the TEM images. Furthermore, it was found that the BET of AC(PS) was 1410 m 2 /g, which was higher than that of AC(OP) (1085 m 2 /g) and AC(SP) (900 m 2 /g). The results obtained from XRD mainly indicated the presence of the nickel phosphides phases, which was confirmed with the XPS and TPD analyses. The catalytic tests showed that by raising the process temperature, the total amount of gas and hydrogen increased. Furthermore, Ni/AC(PS) showed a superior catalytic activity. The highest total gas amount (i.e., 7.87 mmol/g bio-oil), together with 37.2 vol.% H 2 , was achieved using Ni/AC(PS) with a 1:10:100 catalyst:bio-oil weight ratio and a mass ratio of 1:10 (bio-oil/water) at T = 550 ◦ C. Keywords: activated carbon; agricultural residue; mesoporosity; nickel phosphide; supercritical water; hydrogen 1. Introduction The increasing world population not only leads to overconsuming nonrenewable fossil resources, which increases their cost and generates geopolitical problems, but exploiting these fossil fuels also emits greenhouse and harmful gases (CO x , NO x , SO x ). Hence, implementing new practices as a replacement for fossil fuels and that utilize alternative renewable energy sources in the near future is urgent. In this line, worldwide industrial hydrogen demand reached 95 Mts/year in 2021, being satisfied by steam reforming of natural gas or steam cracking of naphtha, and this is expected to increase to 115 Mts/year by 2030. Apart from its use as an industrial feedstock, hydrogen is also regarded as a clean energy carrier (since it only releases H 2 O during its combustion) that has the potential to replace traditional fossil fuels in stationery and heavy transportation (mass transport, aviation, and naval sectors) applications. Governments around the world are implementing policies and measures for greening hydrogen production [1]. Clean hydrogen can be generated from fossil fuels with carbon capture, biomass, or water, through thermal, electrolytic, or photolytic processes [2–4]. Biomass can be used to produce hydrogen through industrial processes that have already been commercially deployed for fossil Catalysts 2023, 13, 854. https://doi.org/10.3390/catal13050854 https://www.mdpi.com/journal/catalysts