Arjan W. Kleij received his MSc (honors) and PhD (cum laude) in chemistry from the University of Utrecht working in the group of Gerard van Koten on the application of dendrimer- and hyperbranched polymer-supported homogeneous catalyst structures. In 2000, he moved to Avantium expanding his research experience, and later he worked at Hexion in the Epoxy & Phenolic Resins Division (EPRD). He joined the group of Javier de Mendoza (UAM, Madrid, Spain) as a postdoctoral fellow in 2002, and continued postdoctoral work with Joost Reek at the University of Amsterdam until 2006. In October 2006, he became a Group Leader at ICIQ.

In 2000 he received an NWO TALENT fellowship, in 2006 an ICREA junior award, was promoted to ICREA professor in 2011, and in 2020 he was endowed with the Scientific Excellence award from the Spanish Chemical Society. He joined Organic Chemistry Frontiers (RSC) as an Associate Editor (2019) and fulfills the same role at Green Synthesis and Catalysis (Elsevier) since 2021. He became a Fellow of the Royal Society of Chemistry (FRSC) in 2021.

His previous and ongoing appointments include the Advisory Board of ChemSusChem, the Editorial Board for the same journal (since 2020), and the Editorial Boards of the Journal of CO₂ Utilization and the Advisory Boards of ChemCatChem and ACS Sustainable Chemistry & Engineering. In 2016 he chaired the first Carbon Dioxide Conversion Catalysis (CDCC-1) conference in Portugal, and in 2019 the 4^th EuCheMS Congress on Green and Sustainable Chemistry (EuGSC-4) in Tarragona. From 2022 onwards, he will be leading the European project “D-Carbonize” being part of an international MSCA-DN-JD network on biocarbon valorization.

His main research interests are in the area of CO₂ valorization catalysis, the development of new reactivity using organic carbonates as modular scaffolds, and the use of renewable compounds in stereoselective transformations and polymer applications. He has (co)authored >210 international publications and 5 patent applications, with total citations around 14000 (h-index 66).