Al_(2)O_(3)晶型对Pt/Al_(2)O_(3)-Cl催化剂物化性质及其催化C_(5)/C_(6)异构化性能的影响

Effect of Al_(2)O_(3) Crystal Phase on Physicochemical Properties of Pt/Al_(2)O_(3)-Cl Catalyst and Its Catalytic Property for C_(5)/C_(6) Isomerization

以拟薄水铝石粉和湃水铝石粉为前驱体,通过挤条成型和焙烧制备了3种不同晶型(γ、θ、η)Al_(2)O_(3)载体,并分别经负载Pt和氯化制备了3种Pt/Al_(2)O_(3)-Cl催化剂(Pt/γ-Al_(2)O_(3)-Cl、Pt/θ-Al_(2)O_(3)-Cl和Pt/η-Al_(2)O_(3)-Cl);采用X射线衍射(XRD)、N_(2)吸附-脱附(BET)、吡啶红外(Py-IR)、透射电镜(TEM)、NH_(3)程序升温脱附(NH_(3)-TPD)等手段表征了3种Al_(2)O_(3)载体及Pt/Al_(2)O_(3)-Cl催化剂,并通过固定床微反装置考察了Pt/Al_(2)O_(3)-Cl催化剂的C_(5)/C_(6)异构化性能。结果表明:γ、θ、η型Al_(2)O_(3)载体经负载Pt和氯化后,晶型不发生改变,Cl含量和酸量均大幅度提高,Lewis酸酸性显著增强,比表面积和孔体积明显下降;Pt/η-Al_(2)O_(3)-Cl催化剂的比表面积和酸量最大,C_(5)/C_(6)异构化活性最高,Pt/γ-Al_(2)O_(3)-Cl次之,Pt/θ-Al_(2)O_(3)-Cl最低;在温度为150℃、压力为3.2 MPa、进料质量空速为1.5 h^(-1)、氢/烃摩尔比为1.0的条件下,Pt/η-Al_(2)O_(3)-Cl催化剂作用下,C_(5)异构化率、C_(6)异构化率和C_(6)选择性分别为77.13%、88.68%和31.87%。

Taking pseudo-boehmite powder and bayerite powder as precursors,three kinds of Al_(2)O_(3) carriers with different crystal phases(γ,θ,η)were obtained by calcination of the extruded precursors,and accordingly three kinds of Pt/Al_(2)O_(3)-Cl catalysts(Pt/γ-Al_(2)O_(3)-Cl,Pt/θ-Al_(2)O_(3)-Cl,Pt/η-Al_(2)O_(3)-Cl)were prepared through Pt loading and chlorination.In addition,three kinds of Al_(2)O_(3) carriers and corresponding Pt/Al_(2)O_(3)-Cl catalysts were characterized by means of X-ray diffraction(XRD),N_(2) adsorption-desorption(BET),pyridine infrared spectroscopy(Py-IR),transmission electron microscopy(TEM),and temperature programmed desorption of NH_(3)(NH_(3)-TPD).The catalytic property of Pt/Al_(2)O_(3)-Cl catalysts for C_(5)/C_(6) isomerization was investigated by fixed-bed microreactor.The results show that after Pt loading and chlorination,the crystal phases ofγ-,θ-andη-Al_(2)O_(3) carriers remain unchanged,both the content of Cl and the amount of acid increase greatly,the acidity of Lewis acid is improved significantly,and the specific surface area and pore volume decrease obviously;Pt/η-Al_(2)O_(3)-Cl catalyst has the highest specific surface area,acid amount and C_(5)/C_(6) isomerization activity,followed by Pt/γ-Al_(2)O_(3)-Cl and Pt/θ-Al_(2)O_(3)-Cl;under the effect of Pt/η-Al_(2)O_(3)-Cl catalyst,when meeting the following conditions:temperature 150℃,pressure 3.2 MPa,feedstock mass hourly space velocity 1.5 h^(-1),hydrogen/hydrocarbon molar ratio 1.0,the C_(5) isomerization rate,C_(6) isomerization rate and C_(6) selectivity can reach 77.13%,88.68%and 31.87%respectively.