總氮的測定方法:用(yong)氧化燃(ran)燒-化學(xue)發光定氮儀測各餾(liu)分油(you)及尾油(you)中的總氮
氮(dan)(dan)(dan)(dan)(dan)(dan)化(hua)(hua)(hua)物(wu)(wu)按其氮(dan)(dan)(dan)(dan)(dan)(dan)原(yuan)子(zi)(zi)(zi)(zi)在分(fen)子(zi)(zi)(zi)(zi)中是(shi)否(fou)有孤對(dui)電子(zi)(zi)(zi)(zi)而分(fen)為(wei)堿性(xing)氮(dan)(dan)(dan)(dan)(dan)(dan)化(hua)(hua)(hua)物(wu)(wu)和(he)(he)非堿性(xing)氮(dan)(dan)(dan)(dan)(dan)(dan)化(hua)(hua)(hua)物(wu)(wu)二(er)大類(lei),由(you)于(yu)堿性(xing)氮(dan)(dan)(dan)(dan)(dan)(dan)化(hua)(hua)(hua)物(wu)(wu)中氮(dan)(dan)(dan)(dan)(dan)(dan)雜原(yuan)子(zi)(zi)(zi)(zi)存在有自由(you)的(de)孤對(dui)電子(zi)(zi)(zi)(zi),即(ji)一(yi)些(xie)胺類(lei)、二(er)氫吲哚(duo)類(lei)和(he)(he)六員環(huan)雜環(huan)氮(dan)(dan)(dan)(dan)(dan)(dan)化(hua)(hua)(hua)合物(wu)(wu),這些(xie)堿性(xing)氮(dan)(dan)(dan)(dan)(dan)(dan)化(hua)(hua)(hua)物(wu)(wu)很容易吸附在催化(hua)(hua)(hua)劑(ji)酸(suan)性(xing)活(huo)性(xing)中心,因(yin)此(ci)對(dui)催化(hua)(hua)(hua)劑(ji)的(de)毒性(xing)很大。有分(fen)子(zi)(zi)(zi)(zi)篩的(de)催化(hua)(hua)(hua)劑(ji)比無定型催化(hua)(hua)(hua)劑(ji)更(geng)怕(pa)堿性(xing)氮(dan)(dan)(dan)(dan)(dan)(dan)化(hua)(hua)(hua)物(wu)(wu),這是(shi)因(yin)為(wei)有機堿氮(dan)(dan)(dan)(dan)(dan)(dan)化(hua)(hua)(hua)物(wu)(wu)在催化(hua)(hua)(hua)劑(ji)上吸附與酸(suan)堿強度有關,分子(zi)篩酸性(xing)比無(wu)定形(xing)強,而(er)脫(tuo)附(fu)(fu)與溫(wen)(wen)度有關,分子(zi)篩催化劑(ji)反應溫(wen)(wen)度相(xiang)對低(di),脫(tuo)附(fu)(fu)慢。
氮(dan)化(hua)物(wu)不僅(jin)影響(xiang)催(cui)化(hua)劑的穩定性,對催(cui)化(hua)劑積炭也(ye)有(you)很大影響(xiang)。日本有(you)些研究表明催(cui)化(hua)劑結炭成分(fen)含氮(dan)量(liang)遠高于油(you)中(zhong)含氮(dan)化(hua)合(he)物(wu)含量(liang)。有(you)學者認為,中(zhong)小(xiao)型含氮(dan)化(hua)合(he)物(wu)是生(sheng)焦生(sheng)碳的前(qian)驅物(wu),芳(fang)烴及(ji)氮(dan)化(hua)合(he)物(wu)受催(cui)化(hua)劑吸附過強(qiang),集中(zhong)在B酸分子中(zhong)心時間過(guo)長發(fa)生縮聚(ju)反應生成(cheng)積(ji)炭覆蓋了活(huo)性表面,造成(cheng)裂化催化劑活(huo)性下(xia)降。實(shi)驗室數據也(ye)表明Ni-Mo系(xi)催化劑在相同轉(zhuan)化率的條(tiao)件(jian)下氮含量2000ppm以及(ji)0ppm兩種原料,其反應溫度差可以達到85℃,對貴重(zhong)金屬(shu)催化劑的影(ying)響更大(da),達到110℃。當氮(dan)含量由500ppm增加到(dao)1300ppm時,催化劑的(de)失活率增加(jia)近3倍。因此在各(ge)項指標中(zhong)(zhong)首要關注的是原料中(zhong)(zhong)的氮含量。與(yu)眾多(duo)國外原油(you)相比,我國原油(you)的特(te)點是多(duo)數含(han)硫少含(han)氮(dan)高,因此加工我國陸上原油(you)時,對原油(you)中(zhong)的氮(dan)含(han)量(liang)應倍(bei)加關注(zhu)。
總氮的測定方法:用氧化(hua)燃燒-化(hua)學發(fa)光定氮儀測各餾(liu)分油(you)(you)及(ji)尾油(you)(you)中的總氮。
總氮的測定儀器:TN-100型化學發光定氮儀
文(wen)章來源于:江蘇(su)雙誠分(fen)析儀(yi)器有限公司