以聚硅氧烷作为改性剂,通过液相硅沉积表面修饰对 HZSM-5分子筛吸附剂进行了择形功能化改性,采用 X 射线衍射(XRD)、NH3-TPD、比表面积与孔径分析和热重分析(TGA)等手段对改性前后的吸附剂进行了表征。分别采用液相吸附法和气相吸附法研究了ZSM-5择形分子筛对于对二甲苯(pX)和间二甲苯(mX)混合物的择形吸附分离效果,考察了硅沉积改性程度、液相吸附及气相吸附工艺条件对硅沉积修饰分子筛Si/ZSM-5择形吸附分离性能的影响。研究结果表明,分子筛吸附剂中介孔体积随着硅沉积改性次数增加而减少,而微孔体积改变较小,但4次硅改性后的分子筛吸附剂的晶体结构未发生明显变化。同时,随着硅沉积改性次数的增加,分子筛吸附剂的吸附量减小,而吸附剂的择形吸附分离系数βpX/mX增大；另一方面,气相热解吸得到的 pX/mX 选择性高于液相解吸法,并且二氯甲烷作为液相解析剂的 pX/mX 择形选择性高于甲苯和环己烷解析剂。吸附重量动态分析测试结果表明,Si/ZSM-5(0)、Si/ZSM-5(2)和 Si/ZSM-5(4)的平均吸附容量分别为102．1,82．12和71．84 mg/g,pX & mX二甲苯混合物的扩散速率随着硅沉积改性程度的增加而明显减小。
The HZSM-5 molecular sieve adsorbent was modified using polysiloxane as modifier and were charac-terized by means of X-ray diffraction (XRD),NH3-TPD,Surface Area and pore size analysis and thermogravi-metric analysis(TGA).The effects of silicon deposition degree,liquid phase adsorption and gas phase adsorp-tion process conditions on the shape-selective adsorption performance were investigated using liquid phase ad-sorption and gas phase adsorption.It was concluded that with the increase of deposited silica,the mesopore vol-une reduced,the micropore volume hardly changed and the crystal structure of adsorbents have not changed af-ter the fourth deposition.Meanwhile the average adsorption capacities decrease while the selectivy of p-xylene increased;on the other hand,the p-xylene selectivity of the gas phase thermal desorption was higher than that of liquid phase desorption,and the shape selectivity of dichloromethane as desorption solution is higher than that of tolune and cyclohexane.Adsorption gravimetric test results show that the average adsorption capacity of Si/ZSM-5(0),Si/ZSM-5(2)and Si/ZSM-5(4)were 102.1,82.12 and 71.84 mg/g and the diffusion rate of xylene mixture decreases with the increase of deposited silica .
参考文献
| [1] | Guo Guoqing;Long Yingcai .Advances of technology in the adsorptive separation of para-xylene[J].Shanghai Chemical Industry,2000,2:24-27. |
| [2] | Luo Yiqing;Sun Changjiang .Progress of C8 aromatic hy-drocarbon separation technology[J].Modern Chemical Industry,2005,25(8):23-26. |
| [3] | Tourani, S.;Baghalha, M.;Khorasheh, F.;Behvandi, A. .Equilibrium modeling of xylene adsorption on molecular sieves[J].Fluid Phase Equilibria,2010(1):54-59. |
| [4] | Weitkamp J. .Zeolites and catalysis[J].Solid state ionics,2000(1/2):175-188. |
| [5] | Roberto Millini;Francesco Frigerio;Giuseppe Bellussi;Giannino Pazzuconi;Carlo Perego;Paolo Pollesel;Ugo Romano .A priori selection of shape-selective zeolite catalysts for the synthesis of 2,6-dimethylnaphthalene[J].Journal of Catalysis,2003(2):298-309. |
| [6] | Broughton D B;Neuzil R W;Pharis J M et al.The parex process for recovering paraxylene[J].Chemical Engineering Progress,1970,66(9):70-75. |
| [7] | Otani S;Akita S;Iwamura T et al.Separation process of co-mponents of feed mixture utilizing solid sorbent[P].US:3761533,1973. |
| [8] | Ash G;Barth K;Hotier G et al.Eluxyl:a new paraxy-lene S-eparation process[J].Rev IFP,1994,49(5):541-549. |
| [9] | Le Yinghong;Tang Yi;Gao Zi .Studies on the control of pore-opening size of HZSM-5 and its shape-selective ad-sorption[J].ACTA CHIMICA SINICA,1996,56:248-252. |
| [10] | Le Yinghong;Tang Yi;Kan Yongzhi et al.Pore size control of NaY zeolite by chemical liquid deposition and shape-selective separation[J].ACTA CHIMICA SINICA,1996,54:591-597. |
| [11] | Ello S;Mash M;Pietro D et al.Separation of xylenes on Y zeolites.1.Determination of the adsorption equi-librium parameters,selectivities,and mass transfer co-efficients through finite bath experiments[J].Industrial and Engineering Chemistry:Process Design and Development,1982,21(3):440-445. |
| [12] | Zhu Zhirong;Hou Min;Chen Qinglin et al.Study of ethylbenzene shape-selective disproportionation on ZSM-5 modified through silica modification[J].Petrochemi-cal Technology,2004,33:1006-1007. |
| [13] | 杨超,赵天波,周涵.甲苯歧化反应物与产物在ZSM系分子筛孔道中扩散特性的分子模拟[J].石油学报（石油加工）,2006(06):14-19. |
| [14] | Scherzer J .Dealuminated faujasite-type structures with SiO2/Al2 O3 ratios over 100[J].Journal of Catalysis,1978,54(2):285-288. |
| [15] | 王春蓉.热重分析改性分子筛吸附分离二甲苯的研究[J].武汉工程大学学报,2007(02):13-15. |
| [16] | 张薄,辜敏,鲜学福.炭分子筛的结构和表面性质对其吸附分离CH4／N2和CO2／N2的影响[J].功能材料,2012(20):2858-2862. |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%