3-甲基啶於Bi-V-20(V/Bi= 4)觸媒上之氨氧化反應發現在溫度 430C、
空間流速 2400ml/h,g及氣體莫耳進料比(3-甲基啶:氧氣:氨氣)為1:1:1
的反應條件下,轉化率可達93%,主要反應產物菸鹼之選擇率為90%.總反
應速率 (Rt)及菸鹼生成速率(Rcn)皆隨3-甲基啶分壓的增加而減少.
當氧分壓增加時,Rt亦增加,而在高分壓下則維持一定,對於Rcn的影響也如
此,唯於高溫時卻有先增後降的趨勢,其主要原因乃二氧化碳逐漸增加之
故.氨分壓對Rt並沒有影響,但Rcn隨氨分壓的增加而明顯增加,啶的生成
量則隨之減少.此外,在相同的氣體進料比為1:1:1之下,使用27300ml/h,g
和9000ml/h,g兩種空間流速分別進行反應,結果顯示,無論低轉化率或高轉
化率,在溫度於 430C時菸鹼的選擇率均為最高.對動力學之研究:冪級數
法求得菸鹼生成速率(Rcn,calcd.)及總反應速率(Rt,calcd.)對3 -甲基
、氧氣和氨氣的反應級數各別為-1.32、.52、. 17及-1.28、.60
、.085,前者之活化能為157.55KJ/mol,後者為174.34KJ/mol.
The ammoxidation of 3-picoline to nicotinonitri -le over Bi-
V-20 catalyst was studied. The conver- sion reached to 93%
under the reaction condition: temperature 430C、space velocity
2400ml/h,g and feed ratio(3-picoline:oxygen:ammonia) of 1:1:1.
The selectivity of nicotinonitrile was 90%. The total reaction
rate(Rt) and the formation rate of nicoti- nonitrile(Rcn) were
both decreased with increasing partial pressure of 3-picoline,
increased with in- creasing partial pressure of oxygen and
constant at high partial pressure. Moreover,Rcn was found to
fall down at high temperature,which can be inter- preated as
being due to the formation of carbon di- oxide. Rt was
independent of partial pressure of am -monia but Rcn was
increased with partial pressure. At the reaction temperature of
430C,the feed ratio of 3-picoline:oxygen:ammonia=1:1:1,and the
space ve -locity of 27300ml/h,g and 9000ml/h,g,the selectivi
-ty of nicotinonitrile reached to maximun with re- gardness of
low conversion and high conversion. The kinetic study showed
that the reaction orders of power-law of Rcn,calcd.and Rt,
calcd. were -1.32、 .52、.17and -1.28、.6、.085,respectively,
with res- pect to 3-picoline、oxygen and ammonia. The active
energy was estimated to be 157.55KJ/mol for the for -mer and
174.34KJ/mol for the later.