ZnSn(OH)6的热分解动力学

物理化学学报( Wuli huarue xuebao)JulyActa Phys.-Chim.Sin.,2007,23(7):1095-10981095[Notewww.whxb.pku.edu.cnZnSn(OH)6的热分解动力学张予东李宾杰2徐翔民2李德亮1(河南大学化学化工学院河南开封475001;2河南大学特种功能材料重点实验室,河南开封475001)摘要:用 TG/DTG联用技术,在25、50、100、150200K·min2不同线性升温条件下,研究了 ZnSn(OH)的热分解过程结果表明,在氮气气氛下, ZnSn(OH)在298873K范围内发生了一步分解其失重率与理论计算值相符应用非等温多重扫描速率法对热分解过程进行了动力学分析,ZnSn(OH)在氮气中分解的活化能E=12877k.mol-,指前因子lgA)=10.61,机理函数为 Mample单行法则关键词: TG/DTG;热分解;机理;动力学中图分类号:O642;0643;06116Thermal Decomposition Kinetics of ZnSn(oH)6ZHANG Yu-Dong LI Bin-Jie XU Xiang- Min" LI De-Liang(College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475001, Henan Province, P. R. China;Laboratory for Special Functional Materials, Henan University, Kaifeng 475001, Henan Province, P. R. ChinaAbatract: The thermal decomposition processes of Zn Sn(OH) were studied using TG/DTG at various heating ratesof 2.5, 5.0, 10.0, 15.0, 20.0 K. min. The results showed that the decomposition proceeded through one step innitrogen atmosphere at the temperature range from 298 to 873 K. a good agreement was found between the mass lossof the thermal decomposition of Zn Sn(OH) and the theoretical mass loss. The thermal decomposition kinetics wasinvestigated employing non- isothermal multiple scanning method. The activation energy for the decompositionreaction of ZnSn(OH) was determined to be E=128. 77 kJ.- in nitrogen atmosphere and the pre-exponential factorof its kinetics equations was calculated to be lg(A/s-)10.61. The mechanism function was obtained to be mampleKey Words: TG/DTG; Thermal detion: Mechanism: Kinetics阻燃剂正随着高分子材料的广泛应用而迅速发法研究了材料的热稳定性.Xu和 Donald等用热展羟基锡酸锌由于具有无毒、阻燃和抑烟的特性,分析法考察了羟基锡酸锌添加到软质聚氯乙烯越来越受到人们的关注,有可能成为Sb2O2的替代(PVC)后材料的分解变化,研究了其对软质PVC的品之一闆.羟基锡酸锌受热分解生成锡酸锌并脱水吸阻燃和抑烟作用.但到目前为止,关于羟基锡酸锌的热,在高温下锌与锡对脱卤化反应具有催化作用,热分解动力学研究还未见报道本文利用非等温多从而起到阻燃抑烟效果.所以,研究羟基锡酸锌的分重扫描速率法研究了羟基锡酸锌的热分解动力学,解动力学对于研究其分解阻燃机理十分重要.为进一步研究该物质的阻燃机理提供有益的信息热分析技术已被广泛应用于研究阻燃材料的热稳定性、分解机理和热分解动力学. Cusack等将1YH中国煤化工羟基锡酸锌加入到系列溴代聚酯树脂中,用热分析CNMHG品)在瑞士MurReceived: December 27, 2006; Revised: March 20, 2007; Published on Web: May 10, 2007Correspondingauthor.Email:zyd71@henu.edu.cn;Tel+86378-2192河南大学自然科学基金重点项目(XKO6ZD003资助C Editorial office of Acta Physico-Chimica Sinica1096Acta Phys.-Chim. Sin, 2007Vol 23Toledo TG/SDTA851型热分析仪上进行.动态氮气基本一致气氛,流速为40mL·min-.样品在测试前用玛瑙研22非等温分解动力学钵小心研磨,以使试样粒度降低并均匀,从而改善传22.1求取活化能E热;测量温度范围为298到873K;升温速率分别为通过非等温分解动力学研究可揭示ZnSn(OH25、5.0、10.0、15.0、20.0K分解的反应机理,获得其最概然机理函数以及相应的动力学参数表1列出了在5种不同升温速率(β)2结果与讨论下, ZnSn(OH受热分解时的DTG峰温T用多重扫21热行为、热分解机理描速率法( multiple scanning method), Flynn-waZnSn(OH的典型TGDG曲线如图所示(在氮 Ozawa(FWO)法2(1), Kissinger法(2)和 Starink气中升温速率为25K·min+,ZnSn(OH在463K时法叫(3)处理这些数据,获得相应的活化能E和指前开始分解,逐渐脱去羟基生成锡酸锌和水,到873K因子A:时热重曲线呈水平,表明此时产物已完全变成锡酸 Flynn-Wall-Ozawa法:锌,失重率为1897%,与理论值1888%基本一致Ig B=lg(0.4567E其反应方程式如下:RG(α)-2315RTZnSn(OH→ EnSo+3HOKissinger法:DTG曲线上仅有一个峰,与TG曲线上失重的台阶对应,表明 ZnSn(OH的热分解过程为一步分解.Starink法由ZnSn(OH在氮气中的TG曲线图2)可知,不同升温速率下的TG曲线均相吻合,说明其失重速率M是品=Ck式中,a为转化率,R为普适气体常数,G(a)为积分机理函数,C为常数由表2可知,用三种多重扫描速率法所获得的8-2.5.min活化能E值非常接近,而且线性系数和标准偏差的m0数值都表明实验数据代入的方程具有良好的线性表3列出了不同加热速率下 ZnSn(OH)热分解过程0004的基本数据0.005222判断反应是否一步反应300400500600700800900用FWO方程(1)和 Friedman方程(4)根据等转化率法求算活化能,得到不同a对应的E值(表4)图1znSn(OH)6的TG/DTG曲线Friedman方程Fig 1 TG/DTG curves of ZnSn(oH)6表1不同加热速率下ZnSn(OH)的DTG曲线的峰温Table 1 Peak temperatures(T, )of DTG curves atB/(K")(from left to right)various heating rates(B)9525,50,10.0,15.0.20.0150TK47799485.66496.525029950731表2用多重扫描速率法获得的热分解动力学参数Table 2 Kinetic parameters of thermal decompo-sition obtained using multiple scanning methods中国煤化工093002567CNMHG0.90900313112znSn(OH)在不同加热速率下的TG曲线13230Fig 2 TG curves of ZnSn(OH) atF-W-0: Flynn-Wall-Ozawa equation; E: activation energdifferent heating ratesr linear coefficient: SD: standard deviationNo.7张予东等:ZnSn(OH)的热分解动力学1097表3不同加热速率下 ZnSn(OH)k热分解过程的基本数据Table 3 Basic data of thermal decomposition of ZnSn(OH) at various heating ratesConversion rate(a)k 10 dadT/K- T/K 10(da/dT)/K- T/K 10'(do/dT)/k- T/K 10/(da/dT/K-10(da/dT/k-46126267467932.47478.123.01187649094248467.123.77474.183.52184803.18490007494212.8846942423476623.99487.473.41495293.74499653018083492114.10497574.00502053.76475.2618273494504403.93484.565.08496.225018l50663478.755.35486.37498.234.284.305089351138482424490.165025250833514.17184.57492353.8105.03511075]7.703513.6650899515553.3l522973.48In[(m )=In(Af(a)]-k表4不同加热速率下ZnSn(OH)的TG数据由式(1)和(4)所得的活化能由表4可见,用FWO法求得的反应活化能 Table4 Activation energies(E) obtained by TG data(020≤a≤0.80)比用 Friedman法求得的略高,但of Zn Sn(OH) according to the Eqs. (1)and (4)atvarious heating rates二者随着α的增大变化平稳,分解反应的活化能变化不大,分解反应具有类似的变化规律,这说明 onversion rate() e w-o method friedman methodZnSn(OH6的分解反应很可能是一步反应同时,由02013986121.13ZnSn(OH)的DTG曲线上仅有一个峰的变化也可以说明这一点125.10035223最概然机理函数的判定微商法 Achar-Brindly-Sharp(ABS)方程吗133.8512202Ef(a)drl18.77积分法 Coats-Redfern(CR)方程吗130.221178l12839114.5511390123.18117,71将实验数据a、T、ddT代入上述两个方程,结合43117.06种常用的固体反应动力学函数fa)和G(a),根据l31.50线性优劣和标准偏差大小,微商法与积分法结果的示取表2和表5中结果的平均值得ZnSn(OH分解的致性,发现No.6基本符合上述条件,如表5所“动力学三因子 kinetic triplet分别是,E=128表5用CR(Eq(6)和ABS(Eq5)法计算所得ZnSn(OH6分解过程的动力学参数Table 5 The kinetics parameters of thermal decomposition obtained by C-R(Eq- (6))and A- B-s(Eq- (5)methodsC-R methodA-B-S methodFunction No tIE(kJ·mol)099670.03513127860.98l1007951134.4512.1509983002521中国煤化工0.99690.03373yHECNMH1501093099510.04054119310.98980.060500.98400.07988Average E value 127.24l098Acta Phys.-Chim Sin, 2007VoL 23kJ·mol,lg(A/s+)=1061,反应的机理函数系 Lampl2005,21(7:752[岳林海金达莱,吕德义徐铸德物理化学单行法则,为一级反应,反应的机理为随机成核,随学报,2005,21():752]后生长机理反应的微分形式为,a)=1-a;积分形o;wnwH: 1ao, Y. 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