影(ying)響汽(qi)油氧化安定性的因素

汽油(you)在常(chang)溫和液相時(shi)抵抗大氣(或氧(yang)氣)的(de)作用(yong)而保持其性(xing)能不發(fa)(fa)生(sheng)變(bian)化的(de)能力，叫氧(yang)化安(an)定性(xing)。汽油(you)在貯存(cun)和使用(yong)過程中，常(chang)常(chang)發(fa)(fa)現汽油(you)顏色變(bian)深，產生(sheng)沉淀物(wu)，含(han)鉛汽油(you)還會(hui)出(chu)現灰(hui)白色沉淀。這(zhe)都是因為汽油(you)中某些成分被空氣中氧(yang)氣氧(yang)化的(de)結(jie)果。

影響其(qi)汽(qi)油(you)(you)安(an)定性(xing)的(de)(de)(de)根本的(de)(de)(de)原因在于汽(qi)油(you)(you)的(de)(de)(de)化(hua)學組(zu)成部分(fen)。組(zu)成汽(qi)油(you)(you)的(de)(de)(de)各(ge)種(zhong)烴(jing)類(lei)的(de)(de)(de)化(hua)學性(xing)質(zhi)是不(bu)同的(de)(de)(de)，芳香烴(jing)、環皖在常(chang)溫下(xia)均不(bu)易和(he)(he)(he)空氣(qi)中(zhong)氧氣(qi)反應。所以，主要由上述三種(zhong)怪(guai)組(zu)成的(de)(de)(de)汽(qi)油(you)(you)的(de)(de)(de)安(an)定性(xing)較好(hao)，汽(qi)油(you)(you)也(ye)就在貯存(cun)和(he)(he)(he)使(shi)用中(zhong)不(bu)易變(bian)質(zhi)。不(bu)飽(bao)和(he)(he)(he)烴(jing)在常(chang)溫液相時，易與空氣(qi)中(zhong)氧氣(qi)發生反應。所以，汽(qi)油(you)(you)中(zhong)如含有較多的(de)(de)(de)不(bu)飽(bao)和(he)(he)(he)烴(jing)，安(an)定性(xing)就差(cha)，生成膠質(zhi)等而導(dao)致(zhi)汽(qi)油(you)(you)變(bian)質(zhi)。另外汽(qi)油(you)(you)中(zhong)各(ge)種(zhong)非烴(jing)類(lei)化(hua)合物也(ye)是引起汽(qi)油(you)(you)氧化(hua)變(bian)質(zhi)的(de)(de)(de)重要因素。

直餾汽(qi)(qi)油(you)中不(bu)含(han)不(bu)飽和(he)烴(jing)(jing)，其(qi)(qi)安(an)(an)(an)定(ding)性(xing)很好；部分二次加工汽(qi)(qi)油(you)中含(han)有(you)(you)大(da)量(liang)不(bu)飽和(he)烴(jing)(jing)及非烴(jing)(jing)化(hua)(hua)合(he)物，其(qi)(qi)安(an)(an)(an)定(ding)性(xing)較差。汽(qi)(qi)油(you)在(zai)貯存和(he)使(shi)(shi)用(yong)中，易變(bian)(bian)(bian)質(zhi)(zhi)(zhi)生膠或生成(cheng)(cheng)有(you)(you)機酸。特別是(shi)(shi)不(bu)飽和(he)短中的(de)(de)二烯烴(jing)(jing)最不(bu)安(an)(an)(an)定(ding)，很容易氧化(hua)(hua)。盡管汽(qi)(qi)油(you)中有(you)(you)時含(han)有(you)(you)的(de)(de)二烯烴(jing)(jing)量(liang)非常少，但(dan)卻能使(shi)(shi)汽(qi)(qi)油(you)的(de)(de)安(an)(an)(an)定(ding)性(xing)顯著變(bian)(bian)(bian)差。此外，汽(qi)(qi)油(you)中的(de)(de)硫(liu)、氮、氧的(de)(de)非烴(jing)(jing)類(lei)化(hua)(hua)合(he)物，對(dui)汽(qi)(qi)油(you)安(an)(an)(an)定(ding)性(xing)都有(you)(you)不(bu)同程度(du)的(de)(de)影響。一般來說(shuo)(shuo)，上述三類(lei)非烴(jing)(jing)化(hua)(hua)合(he)物含(han)量(liang)越(yue)大(da)，其(qi)(qi)汽(qi)(qi)油(you)的(de)(de)變(bian)(bian)(bian)質(zhi)(zhi)(zhi)速度(du)越(yue)快。值(zhi)得注意的(de)(de)是(shi)(shi)，汽(qi)(qi)油(you)氧化(hua)(hua)以后生成(cheng)(cheng)膠質(zhi)(zhi)(zhi)，膠質(zhi)(zhi)(zhi)本身具(ju)有(you)(you)氧化(hua)(hua)催化(hua)(hua)作用(yong)。也(ye)就(jiu)是(shi)(shi)說(shuo)(shuo)，膠質(zhi)(zhi)(zhi)會加速汽(qi)(qi)油(you)的(de)(de)氧化(hua)(hua)生膠。認識這(zhe)一規律(lv)對(dui)汽(qi)(qi)油(you)的(de)(de)使(shi)(shi)用(yong)有(you)(you)著重(zhong)要意義，因(yin)為它(ta)告訴人(ren)們(men)一旦發現汽(qi)(qi)油(you)開始生膠，在(zai)肢質(zhi)(zhi)(zhi)急劇增加前，就(jiu)應及時安(an)(an)(an)排使(shi)(shi)用(yong)以防止引起汽(qi)(qi)油(you)嚴(yan)重(zhong)變(bian)(bian)(bian)質(zhi)(zhi)(zhi)。

外部條件對汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)氧(yang)(yang)化(hua)(hua)安定(ding)性(xing)的(de)(de)影響(xiang)外部條件包括強度(du)、氧(yang)(yang)氣(qi)、水分(fen)(fen)及金(jin)屬催(cui)(cui)化(hua)(hua)等的(de)(de)影響(xiang)。溫(wen)度(du)升高(gao)時(shi)，汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)氧(yang)(yang)化(hua)(hua)速度(du)加快。當(dang)環(huan)境(jing)(jing)溫(wen)度(du)在c-or時(shi)，汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)氧(yang)(yang)化(hua)(hua)生膠的(de)(de)進(jin)程很(hen)慢(man)；當(dang)環(huan)境(jing)(jing)溫(wen)度(du)高(gao)于15°e時(shi)，汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)氧(yang)(yang)化(hua)(hua)生膠的(de)(de)進(jin)程加快；如(ru)環(huan)境(jing)(jing)溫(wen)度(du)高(gao)于35°e時(shi)，汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)氧(yang)(yang)化(hua)(hua)生膠的(de)(de)進(jin)程將(jiang)隨著(zhu)(zhu)(zhu)貯存(cun)(cun)時(shi)間(jian)的(de)(de)延長(chang)而(er)成倍增加。空(kong)(kong)氣(qi)與(yu)油(you)(you)(you)(you)面(mian)的(de)(de)接觸(chu)量(liang)大(da)小及液(ye)面(mian)上空(kong)(kong)氣(qi)變換(huan)強度(du)對汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)的(de)(de)安定(ding)性(xing)有(you)(you)著(zhu)(zhu)(zhu)很(hen)大(da)的(de)(de)影響(xiang)。貯油(you)(you)(you)(you)容器中(zhong)汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)裝滿的(de)(de)程度(du)，決定(ding)著(zhu)(zhu)(zhu)汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)與(yu)空(kong)(kong)氣(qi)的(de)(de)接觸(chu)量(liang)。貯油(you)(you)(you)(you)容器是否密(mi)封，決定(ding)著(zhu)(zhu)(zhu)汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)液(ye)面(mian)空(kong)(kong)氣(qi)的(de)(de)變換(huan)強度(du)。如(ru)空(kong)(kong)氣(qi)與(yu)汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)液(ye)面(mian)接觸(chu)量(liang)大(da)且變換(huan)強度(du)大(da)，則汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)的(de)(de)氧(yang)(yang)化(hua)(hua)變質(zhi)速度(du)就會增大(da)。金(jin)屬對汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)的(de)(de)氧(yang)(yang)化(hua)(hua)起著(zhu)(zhu)(zhu)催(cui)(cui)化(hua)(hua)作用(yong)，不同的(de)(de)金(jin)屬所起的(de)(de)催(cui)(cui)化(hua)(hua)作用(yong)有(you)(you)很(hen)大(da)差(cha)別。其中(zhong)銅(tong)的(de)(de)催(cui)(cui)化(hua)(hua)作用(yong)強，其次是鉛。據(ju)實驗證明，銅(tong)能使(shi)汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)氧(yang)(yang)化(hua)(hua)生臟的(de)(de)速度(du)增加6倍。在汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)發動(dong)機燃料(liao)供給系(xi)中(zhong)，不僅(jin)有(you)(you)銅(tong)(如(ru)銅(tong)濾(lv)網等)，而(er)且有(you)(you)鉛反如(ru)容器內壁鍍鉛層)。因(yin)而(er)，宜在汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)箱長(chang)期(qi)貯存(cun)(cun)汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)。因(yin)此，貯存(cun)(cun)汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)時(shi)，應盡量(liang)使(shi)用(yong)大(da)容器。少用(yong)或(huo)不用(yong)小油(you)(you)(you)(you)桶或(huo)油(you)(you)(you)(you)箱貯油(you)(you)(you)(you)。汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)中(zhong)含有(you)(you)水分(fen)(fen)，也會使(shi)汽(qi)(qi)(qi)(qi)油(you)(you)(you)(you)氧(yang)(yang)化(hua)(hua)速度(du)加快。故應盡量(liang)避(bi)免水分(fen)(fen)進(jin)入油(you)(you)(you)(you)中(zhong)。