The　carboxyl　functionalized　ionic　liquid　([mim(CH2)3COOH]Cl)　was　prepared　as　a　linker　to　combine　phosphotungstic　acid　(HPW)　and　Zr(IV)　ion.　The　obtained　[mim(CH2)3COO]3PW-Zr　composite　acted　as　a　heterogeneous　catalyst　for　removing　DBT　from　liquid　fuel　with　H2O2　as　an　oxidant.　As　a　result,　[mim(CH2)3COO]3PW-Zr　possessed　high　catalytic　activity　in　extractive　and　catalytic　oxidative　desulfurization　(ECODS).　Moreover,　the　[mim(CH2)3COO]3PW-Zr　was　further　exploited　to　grow　on　the　surface　of　PEI/silica　gel.　And　the　fabricated　large-grained　Zr-PWIL@PEI/silica　gel　was　used　in　the　continuous　ECODS　process,　and　the　removal　of　DBT　could　still　reach　more　than　95%　after　running　continuously　for　16　h.　More　importantly,　the　synergistic　catalytic　mechanism　between　HPW　and　Zr(IV)　in　the　ECODS　process　has　been　investigated　in　detail　by　experiments　and　DFT　calculations.　As　a　result,　a　plausible　mechanism　has　been　proposed　and　verified,　which　contains　two　parts:　the　Lewis　acidic　center　activating　H2O2　to　form　superoxide　ion　radicals　([rad]OOH),　and　the　[rad]OOH　oxidizing　HPW　to　peroxotungstate　(W(O2)n),　which　has　a　high　oxidizability　and　stability.　Thus,　the　effective　combination　of　Zr(IV)　and　HPW　active　sites　is　a　very　effective　strategy　to　promote　desulfurization　efficiency　and　utilization　efficiency　of　H2O2.　Besides,　we　also　found　the　distance　between　the　corresponding　active　sites　of　catalysts　plays　an　essential　role　in　ECODS　reaction　as　it　strongly　influences　the　synergistic　effect　between　different　active　sites.　©　2022　Elsevier　Ltd