中国电机工程学报
中國電機工程學報
중국전궤공정학보
ZHONGGUO DIANJI GONGCHENG XUEBAO
2014年
32期
5757-5762
,共6页
褐煤%水热提质%苯甲酸%苯甲醛%量子化学%密度泛函数
褐煤%水熱提質%苯甲痠%苯甲醛%量子化學%密度汎函數
갈매%수열제질%분갑산%분갑철%양자화학%밀도범함수
brown coal%hydrothermal dewatering%benzoic acid%benzaldehyde%quantum chemistry%density functional theory
水热脱水提质能够有效地脱除褐煤等低阶煤内部水分与含氧官能团，提高褐煤的煤阶及应用价值。选用褐煤的简化含氧模型化合物苯甲酸和苯甲醛，在分子水平上对褐煤的脱氧反应机制进行研究。采用量子化学 B3LYP/6-31G(d)密度泛函数方法，得到水热提质条件下反应过程中各反应物、中间体、过渡态和产物的几何构型和能量变化，进而得到反应过程的热力学和动力学参数。计算结果表明：在水热提质的压力条件下，苯甲酸脱羧基的反应能自发进行，而苯甲醛脱羰基的反应在较低温度时是热力学禁阻的，需要约500K以上时才是热力学可行的。同时，脱羧反应的活化能小于脱羰反应的活化能，说明羧基的反应活性强于羰基，脱除难度较低，所以CO2的生成温度低于CO。
水熱脫水提質能夠有效地脫除褐煤等低階煤內部水分與含氧官能糰，提高褐煤的煤階及應用價值。選用褐煤的簡化含氧模型化閤物苯甲痠和苯甲醛，在分子水平上對褐煤的脫氧反應機製進行研究。採用量子化學 B3LYP/6-31G(d)密度汎函數方法，得到水熱提質條件下反應過程中各反應物、中間體、過渡態和產物的幾何構型和能量變化，進而得到反應過程的熱力學和動力學參數。計算結果錶明：在水熱提質的壓力條件下，苯甲痠脫羧基的反應能自髮進行，而苯甲醛脫羰基的反應在較低溫度時是熱力學禁阻的，需要約500K以上時纔是熱力學可行的。同時，脫羧反應的活化能小于脫羰反應的活化能，說明羧基的反應活性彊于羰基，脫除難度較低，所以CO2的生成溫度低于CO。
수열탈수제질능구유효지탈제갈매등저계매내부수분여함양관능단，제고갈매적매계급응용개치。선용갈매적간화함양모형화합물분갑산화분갑철，재분자수평상대갈매적탈양반응궤제진행연구。채용양자화학 B3LYP/6-31G(d)밀도범함수방법，득도수열제질조건하반응과정중각반응물、중간체、과도태화산물적궤하구형화능량변화，진이득도반응과정적열역학화동역학삼수。계산결과표명：재수열제질적압력조건하，분갑산탈최기적반응능자발진행，이분갑철탈탄기적반응재교저온도시시열역학금조적，수요약500K이상시재시열역학가행적。동시，탈최반응적활화능소우탈탄반응적활화능，설명최기적반응활성강우탄기，탈제난도교저，소이CO2적생성온도저우CO。
Hydrothermal dewatering (HTD) is an effective method to remove the inherent moisture and oxygen functional groups in brown coal. And then the coal rank and application value of brown coal can be upgraded. A comprehensive molecular modeling study was carried out to clarify mechanisms for deoxidization process from brown coal with simplified models (benzoic acid and benzaldehyde). Geometry optimizations of reactants, intermediates, transition states and products were carried out by using density functional theory at the B3LYP/6-31G (d) level. Based on analysis of reaction pathways, the thermodynamic and kinetic parameters were calculated. Results show that the de-carboxyl reaction is a spontaneous process on thermodynamics, while the de-carbonyl reaction is inhibited at a low temperature. At the same time, the activation energy of decarboxylation is also lower than de-carbonyl reaction. It is more difficult to remove carbonyl, and the temperature of the CO2 generator is lower than that of CO.
