(中南大學(xué) 冶金與環(huán)境學(xué)院，長(zhǎng)沙 410083)
摘 要: 針對(duì)現(xiàn)有季銨鹽N263合成工藝毒性大、轉(zhuǎn)型步驟冗長(zhǎng)和設(shè)備要求高等問(wèn)題，以三辛基甲基溴化銨為催化劑、碳酸二甲酯(DMC)為季銨化試劑替代傳統(tǒng)的氯甲烷與N235在高壓反應(yīng)釜中合成甲基碳酸酯季銨鹽，考察反應(yīng)物摩爾比、反應(yīng)溫度、溶劑、催化劑和反應(yīng)時(shí)間等主要因素對(duì)叔胺轉(zhuǎn)化率的影響。結(jié)果表明：在最適宜的條件下，當(dāng)N235與碳酸二甲酯的摩爾比為1:5.6、甲醇與N235的體積比為1:2、三辛基甲基溴化銨催化劑為反應(yīng)體系總質(zhì)量的5%、反應(yīng)溫度為110 ℃、反應(yīng)時(shí)間為8 h時(shí)，叔胺轉(zhuǎn)化率可達(dá)99.39%；該甲基碳酸酯季銨鹽用3 mol/L H2SO4酸洗、0.6 mol/L NaOH堿洗，轉(zhuǎn)型為 季銨鹽；用轉(zhuǎn)型后的 季銨鹽按以下比例配成有機(jī)相：50%轉(zhuǎn)型后的 季銨鹽+30%仲辛醇+20%磺化煤油(體積分?jǐn)?shù))，在25 ℃下用該有機(jī)相萃取鎢礦蘇打浸出模擬料液(105.7 g/L WO3，100 g/L Na2CO3)，相比O/A=2:1，萃取時(shí)間為5 min時(shí)，單級(jí)萃鎢率可達(dá)80.88%，有機(jī)相飽和萃鎢量(以WO3計(jì))為83.92 g/L。
關(guān)鍵字: 甲基碳酸酯季銨鹽；碳酸二甲酯；鎢；轉(zhuǎn)型；溶劑萃取
（School of Metallurgy and Environment, Central South University, Changsha 410083, China）
Abstract:The synthesis of methyl carbonate quaternary ammonium salt in high pressure reactor was investigated by using dimethyl carbonate (DMC) substituting for traditional methylene chloride as alkylating agent, tri-n-octylmethyl- ammonium bromine as catalyst and N235 as tertiary amine material to solve the problems in the existing quaternary ammonium salt extractant N263, such as toxic synthesis process, long transformation step, and high equipment requirements. The influences of molar ratio of reactants, reaction temperature, solvent, catalyst and reaction time on the conversion rate of tertiary amine were inspected. The results show that under the optimal conditions of molar ratio of dimethyl carbonate to N235 5.6, volume ratio of methanol to N235 1:2, catalyst 5% (mass fraction for reaction system), temperature 110 ℃, reaction time 8 h, the highest conversion of tertiary amine can reach 99.39%. The product was totally transformed to quaternary ammonium salt after the treatment of 3 mol/L H2SO4 and 0.6 mol/L NaOH. Under conditions of extraction temperature 25 ℃, phase ratio (O/A) 2:1, extraction time 5 min, with 50% quaternary ammonium salt in 30% sec-octyl alcohols and 20% sulphonated kerosene as extractant (volume fraction), the single-stage extraction rate of tungsten from autoclave-soda leach solution of scheelite which contains 105.7 g /L WO3 and 100 g/L Na2CO3 is 80.88%, and the saturated loading capacity(for WO3) of organic reaches 83.92 g/L.
Key words: methyl carbonate quaternary ammonium salt; dimethyl carbonate; tungsten; transformation; solvent extraction
