Synergistic Effect And Mechanism Of High Temperature Hydrochloric Acid Corrosion Inhibitors For 13Cr Stainless Steel

In the procedures of the exploitation of oil and gas fields,acid-fracturing is always used for enhancing oil and gas productivity.Because of the high temperature and strong acid in the process of acid-fracturing,serious corrosion of metal equipment is inevitable.According to the high temperature and strong acid conditions in the process of acid-fracturing,we are trying to develop a corrosion inhibitor of high temperature and strong acid resistance to reduce the corrosion of metal equipment.First of all,imidazoline quaternary ammonium salts(IM)and benzyl quinoline(QL)were synthesized as the main composition of the inhibitors.Then the synthetic products were identified by Fourier transform infrared spectroscopy(FTIR)to make sure they are what we wanted.Secondly,we studied the inhibitors properties with the methods of weight loss(WL),dynamic potential polarization curves(Tafel)and impedance spectroscopy(EIS).Silok,OP-10 and KI were compounded with QL and IM as the additives.The testing results show that: at 140 ?,the add of Silok enhanced inhibition effect of IM.However,the effect of compound corrosion inhibitor is still not obvious.The add of KI greatly strengthen the effect of IM in high temperature and strong acid.But at 170? the effect of IM+KI greatly reduce.At 140? the QL has a high inhibition efficiency.However,when the temperature rise up to 170 ?,the inhibition efficiency of QL significantly decreases.The add of KI also greatly strengthen the inhibition effects of QL at 170 ?In addition,the inhibitors' mechanism were studied by zero charge potential(PZC)test and the molecular frontier molecular orbital distribution.The results of PZC test displayed: the add of QL,IM and KI makes the capacitor value of system reduce,and makes charged state of iron surface change.EHOMO and ELUMO show that: OP-10 and Silok is more likely to lose electrons than QL and IM,but QL and IM is more easier to accept electronics than OP-10 and Silok.This makes inhibitors molecular electronics achieve a balance by gaining and losing.