The　substitution　of　air　with　O2/CO2　atmosphere　is　a　promising　solution　for　CO2　recirculation　during　coal　gasification.　However,　a　comprehensive　understanding　on　the　formation　mechanism　of　PAHs　and　soot　under　different　conditions　is　necessary　to　reduce　their　emissions.　This　work　presents　simulation　results　of　a　two-stage　entrained　flow　coal　gasifier　in　a　250　MW　industrial-scale　plant　using　detailed　chemistry.　The　influences　of　reductor　temperature　(1000–1200　℃)　and　coal　types　(bituminous　coal,　sub-bituminous　coal,　and　lignite)　on　PAHs　and　soot　formations　from　the　coal　volatiles　in　the　reductor　were　simulated　through　a　detailed　chemical　kinetic　model　under　air　and　O2/CO2　atmospheres.　Results　show　that　2-　and　3-ring　aromatics　are　main　PAHs　products.　Rising　temperature　has　inhibitory　effects　on　PAHs　formation,　especially　for　lignite.　The　O2/CO2　condition　reduces　the　PAHs　yield　compared　with　the　air　condition.　Rate　of　production　analysis　reveals　that　conversion　of　major　PAHs　occurs　mainly　between　PAHs　and　their　radicals.　Vinyl-naphthyl　radical　and　indenyl　radical　play　an　important　role　in　the　acenaphthylene　conversion.　In　addition,　soot　production　increases　with　a　higher　temperature　under　both　air　and　O2/CO2　conditions.　The　O2/CO2　condition　effectively　suppressed　soot　production　through　a　weaker　HACA　surface　growth　route　than　the　air　condition.　lignite　produces　the　least　soot,　and　sub-bituminous　coal　produces　the　most.　This　study　deeply　reveals　the　formation　mechanisms　of　PAHs　and　soot　in　a　two-stage　entrained　flow　gasifier　through　detailed　chemical　kinetic　modeling,　giving　an　insight　into　the　complex　PAHs　and　soot　formations　to　assess　the　design　and　the　operating　condition　of　gasifier　with　O2/CO2　injection.　©　2025　Elsevier　B.V.