超级微波消解-电感耦合等离子体串联质谱法测定MFI型分子筛硅铝比  

Determination of silicon-aluminum ratio in MFI molecular sieve by inductively coupled plasma tandem mass spectrometry with super microwave digestion

作　　者：米彩霞 张静 王佳俊 MI Caixia;ZHANG Jing;WANG Jiajun(Yinchuan University of Energy,Yinchuan 750105,China;Institute of Quality Standard and Testing Technology for Agro-products of Ningxia,Yinchuan 750001,China)

机构地区：[1]银川能源学院,宁夏银川750105 [2]宁夏农产品质量标准与检测技术研究院,宁夏银川750001

出　　处：《冶金分析》2024年第3期8-14,共7页Metallurgical Analysis

基　　金：宁夏回族自治区自然基金(2022AAC03437);宁夏回族自治区银川能源学院(2022-KY-Z-1)。

摘　　要：作为重油催化裂化及甲醇制汽油重要的催化剂,MFI型分子筛的硅铝比是影响其催化性能的主要指标。采用盐酸、硝酸、氢氟酸混酸以超级微波消解法处理样品,克服了高硅样品难以消解完全的问题;采用串联质谱(MS/MS)的氧气质量转移模式,分别设置一级质量过滤器(Q1)和二级质量过滤器(Q2)的质荷比为28、60,控制氧气流量为0.40 L/min测定Si;采用单极杆的氦气碰撞池模式,控制氦气流量为3.0 L/min测定Al;以Ge为内标校正Si,以Sc为内标校正Al,实现了超级微波消解-电感耦合等离子体串联质谱法(ICP-MS/MS)对分子筛中Si和Al的测定,进而计算得到了硅铝比。为了避免Si的挥发损失,对氢氟酸的加入时机进行了考察,结果表明,在微波消解后加入氢氟酸,所测Si含量略高于微波消解前,且相对标准偏差较小,因此认为微波消解后加入氢氟酸可有效避免Si的损失。在优化的实验条件下,Si和Al校准曲线的线性范围分别为50~1000μg/L和5~400μg/L,相关系数均为1.0000,检出限分别为0.0031和0.0014μg/g,定量限分别为0.0102和0.0045μg/g。采用实验方法对MFI型分子筛样品进行测定,Si和Al测定结果均与电感耦合等离子体原子发射光谱法(ICP-AES)基本一致,测定结果的相对标准偏差(RSD,n=7)分别为2.5%、3.1%,加标回收率分别为95%~110%和90%~110%。MFI molecular sieve is an important catalyst for catalytic cracking of heavy oil and methanol-to-gasoline,and the silicon-aluminum ratio is a major index influencing its catalytic performance.The sample was treated by super microwave digestion with hydrochloric acid,nitric acid and hydrofluoric acid,which overcame the problem of difficult digestion of high silicon samples.The oxygen mass transfer mode of tandem mass spectrometry(MS/MS)was adopted to determine Si with the mass-to-charge ratio of the first mass filter(Q1)of 28 and the second mass filter(Q2)of 60,and the flow rate of oxygen was controlled at 0.40 L/min.The helium collision cell mode of unipolar rod was adopted to determine Al with the flow rate of helium as 3.0 L/min.Sc and Ge were selected as the internal standard element for the correction of Si and Al,respectively.The determination of Si and Al in molecular sieve was realized by inductively coupled plasma tandem mass spectrometry(ICP-MS/MS)with super microwave digestion.Therefore,the silicon-aluminum ratio could be calculated.In order to avoid the volatilization loss of Si,the time for addition of hydrofluoric acid was investigated.It was indicated that the determination result of Si was higher when the hydrofluoric acid was added after microwave digestion than that obtained before microwave digestion.Moreover,its corresponding relative standard deviation was lower.Therefore,the addition of hydrofluoric acid after microwave digestion could effectively avoid the loss of Si.Under the optimized experimental conditions,the linear ranges of calibration curve for Si and Al were 50-1000μg/L and 5-400μg/L,respectively.The correlation coefficients were both 1.0000.The limits of detection were 0.0031μg/g and 0.0014μg/g,and the limits of quantification were 0.0102μg/g and 0.0045μg/g,respectively.MFI molecular samples were determined according to the proposed method,and the determination results of Si and Al were basically consistent with those obtained by inductively coupled plasma atomic emission spe

关 键 词：电感耦合等离子体串联质谱法(ICP-MS/MS) 超级微波消解 硅铝比 分子筛 

分 类 号：O657.63[理学—分析化学] TQ424[理学—化学]