不同Pt前躯体对Pt/KL催化剂芳构化性能的影响

为考察不同Pt前躯体对Pt/KL催化剂芳构化性能的影响，分别以Pt(NH₃) ₄ (NO₃) ₂和Pt(NH₃ )₄ Cl₂为Pt前躯体，KL分子筛为载体，制备了TN-Pt/KL和TC-Pt/KL芳构化催化剂，其对应的再生剂为R-TN-Pt/KL和R-TC-Pt/KL。采用XRD、XRF、TGA、BET、TEM、H₂-TPR等分析手段对上述催化剂进行了表征，并以正庚烷为原料，在500  ℃、0.4 MPa、MHSV=1.5 h^-1、n(H₂)/n(n-Heptane)=3的条件下分别对新鲜剂和再生剂的芳构化性能进行评价。结果表明：2种不同的Pt前躯体对新鲜剂上Pt的粒径、比表面积和孔体积影响不大，但 TC-Pt/KL 催化剂上芳构化活性中心更多，且该催化剂上的Pt²⁺与KL分子筛载体之间的相互作用力更强，有利于提高其芳构化活性，减缓Pt颗粒聚集长大；与新鲜剂相比，2种再生剂Pt粒径均明显增大，比表面积和孔体积也明显降低，但R-TC-Pt/KL的物化性质优于R-TN Pt/KL；以Pt(NH ₃ ) ₄ Cl₂为前躯体制备的催化剂具有较优异的芳构化活性和稳定性，2种催化剂的再生性能均较差, TC-Pt/KL催化剂比TN-Pt/KL的再生性能略好。

Influences of Pt Precursors on the Aromatization Performance of Pt/KL Catalyst

To investigate the influence of different Pt precursors on the aromatization performance of Pt/KL catalyst，the aromatization catalysts TN-Pt /KL and TC-Pt /KL were prepared respectively with Pt(NH3)4(NO3)2 and Pt(NH3)4Cl2 as the Pt precursor and KL molecular sieve as the carrier. The corresponding regenerated catalysts are R-TN-Pt/KL and R-TC-Pt /KL. These catalysts were characterized by XRD (X-ray diffraction), XRF (X-ray fluorescence spectromety), BET (N2 physical adsorption), TEM (Transmission electron microscopy), and H2-TPR (H2 temperature programmed reduction). It was found that the two different Pt precursors had little effect on the particle size of Pt, surface area and pore volume on the fresh catalysts, but TC-Pt/KL had more aromatization active centers and the interaction force between Pt2+ and KL molecular sieve was stronger. It is beneficial to improve aromatization activity and slow down the aggregation and growth of Pt particles. Compared with the fresh catalysts, the Pt particle size of the two regenerated catalysts increased significantly, surface area and pore volume obviously decreased, but the physical and chemical properties of R-TC-Pt/KL was better. Using n-heptane as feed, under the conditions of 500℃,0.4MPa,WHSV=1.5h-1,n(H2)/n(n-heptane)=3, the aromatization performance of fresh catalysts and regeneration catalysts was evaluated respectively. The results showed that the catalysts prepared by Pt(NH3)4Cl2 had excellent aromatization activity and stability. The regeneration performance of both catalysts were poor, but compared with TN-Pt/KL, TC-Pt/KL catalyst has a slightly better regeneration performance.