Synthesisand Corrosion Inhibition Ofthe Gemini Surfactants With Hydroxylgroup

Corrosion of carbon steel has become a serious challenge to the oilexploitation and transmission. Hydrogen sulfide, carbon dioxide and othercorrosive gases, as the concomitants of the oil production, have strongcorrosive activity to the metal pipelines and equipments （tubing, casing andgathering pipeline, pump）. It is important to develop the corrosion protectionmethods for H₂S and CO₂. Currently, there have been several methods tocontrol corrosion in the oil and gas production. Using inhibitors has beenacknowledged as one of the most cost-effective methods for corrosioninhibition. Recently, gemini surfactants have potential value as corrosioninhibitor due to their special molecule structure and therefore have become thefocus of researches.In this thesis, a series of novel cationic quaternary ammonium geminisurfactants containing hydroxyl group were synthesized. The inhibitionperformance and mechanism of the gemini surfactants n-3OH-n （n=12,14,16,18） to control corrosion in H₂S and CO₂coexistence environment and CO₂environment were evaluated by weight-loss method and electrochemicalmethods.The main conclusions are as follow:1. The corrosion behavior of the gemini surfactants in H₂S and CO₂ coexistence system at60oC: the effect of the length of hydrophobic groupon the inhibition efficiency obeys the order:14-3OH-14>12-3OH-12>16-3OH-16>18-3OH-18; the effect of concentration of gemini surfactantson the inhibition efficiency is35mg/L>50mg/L>100mg/L>20mg/L>10mg/L; the adsorption of the synthesized gemini surfactants n-3OH-n （n=12,14,16） on carbon steel surface obeys to Langmuir adsorption isotherm.2. In the H₂S and CO₂coexistence environment, the best ratio of the geminisurfactant（12-3OH-12） to corrosion inhibitor（BQ-1） is20%BQ-1+5%12-3OH-12，the optimal using concentration is200mg/L.3. In the corrosive environment containing CO₂, the impact rules of bothhydrophobic carbon chain length and using concentration are consistentwith that in the environmental corrosion of H2S and CO₂; with temperaturerising, the corrosion rate increases and the inhibition effect increasesslightly.4. In the corrosive environment containing CO₂, weight-loss results indicatedthat there is a synergistic effect between gemini surfactant and thiourea.The optium mixing ratio of gemini surfactant to thiourea is1:2.