摘要
采用水蒸气和碱性氨水蒸气在 5 0 0℃下对纳米HZSM 5沸石催化剂进行了水热处理改性 ,并用XRD ,IR ,NH3 TPD和XRF对催化剂进行了表征 .以降低FCC汽油 (≤ 70℃馏分 )烯烃含量为探针反应 ,考察了不同水热处理介质对催化剂酸性质和催化性能的影响 .结果表明 ,经不同介质水热处理后 ,纳米HZSM 5沸石中约 1 0 %的Al2 O3 被脱除 ,总酸量降低 ,导致积炭失活的强酸中心明显减少 ;不同水热处理介质对催化剂的总酸量没有明显影响 ,而对酸中心类型分布的影响较大 .水热处理改性使催化剂活性的稳定性明显改善 ,初始活性降低 .同时 ,水热处理改性降低了催化剂对芳构化反应的催化活性 ,提高了对异构化反应的催化活性 .采用氨水 (0 5mol/L)蒸气处理的纳米HZSM 5催化剂其降烯烃催化活性更为稳定 .在给定的反应条件下 ,FCC汽油的烯烃含量 (φ)由 6 5 9%降低到约 2 6 % ,产物中烯烃、芳烃 (主要是C7～C9芳烃 )和烷烃含量分别保持在2 5 % ,1 9%和 5 5 %左右 。
Nano HZSM 5 zeolite was modified with steam of water and ammonia water (0 25 and 0 5 mol/L) at 500 ℃ respectively. The obtained catalyst samples were characterized by XRD, IR, NH 3 TPD and XRF. The catalytic performance of nano HZSM 5 catalyst for reducing olefin in FCC gasoline (≤70 ℃ fraction) was investigated. The results showed that, after the hydrothermal treatment, about 10% of Al 2O 3 was removed from nano HZSM 5 zeolite, and the amount of acids in nano HZSM 5 zeolite decreased significantly, so did the centers of strong acids causing the deactivation of catalyst by carbon deposit. The hydrothermal media had major effects on the acid type distribution on nano HZSM 5 zeolite while the amount of acids was almost indentical. The activity stability of the catalyst for reducing olefins in FCC gasoline was maintained although the initial activity had a little decrease after the hydrothermal treatment. As a result, the ability of the catalyst for aromatization decreased, so that the content of aromatics decreased and that of iso paraffins increased in the product of gasoline. Considering the activity and stability for reducing the olefins in FCC gasoline, the hydrothermal treatment with steam of ammonia water (0 5 mol/L) was feasible. Under the given reaction conditions, the content ( φ ) of olefins in FCC gasoline could be decreased from 65 9% to ～26%. The content of olefins, aromatics (mainly C 7～C 9) and alkanes in the product were 25%, 19% and 55% respectively, but the octane value was invariable basically.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2003年第12期900-904,共5页
关键词
纳米HZSM-5沸石
水热处理
氨水
酸性质
FCC汽油
烯烃
nano HZSM 5 zeolite, hydrothermo treatment, ammonia water, acid property, FCC gasoline, olefin
