摘要
硅胶载体热活化过程中的局部烧结现象对催化剂的活性和性能有较大的破坏作用。本文利用 XRD、SEM和原位 FTIR等手段对三种热活化硅胶载体进行了研究。研究表明 ,T- 1、T- 3和 T- 4三种硅胶载体发生局部烧结现象的起始温度 Ts值约分别为 90 0℃、60 0℃和 60 0℃ (升温速率 1 0 0℃ /小时 ) ,局部烧结现象将引起硅胶载体非晶程度下降 ,扩散孔分率下降。 SEM观察到了 90 0℃热活化 T- 1硅胶中的局部烧结现象 ,其实质是原级粒子之间相互熔结聚并而增大。原位红外结果则表明 ,局部烧结可能导致了硅胶颗粒内部 Si OSi骨架结构的变化。
In the UNIPOL ethylene gas phase polymerization processes,the thermoactivation process of catalyst supports would affect the properties of both the catalysts and the polymers significantly. In this paper, the thermoactivation processes of three kinds of silica supports have been studied by using XRD、SEM and In situ FTIR methods. New criteria for judging the occurance of local sintering in the thermoactivated silica particles has been supposed. For T 1、T 3 and T 4 silica supports the starting temperatures of local sintering T s are 900℃、600℃ and 600℃ respectively,and the process of the silica supports's thermoactivation could be divided into three stages:(1) ≤200℃,loss of the physisorbed water;(2) 200～T s ℃,disapearing of the phsisorbed water and starting of the dehydroxylation;(3) ≥T s ℃,dehydroxylation,but local sintering ocurred leading to increase of crystallinity of the support. Local sintering was observed in the 900℃ activated T 1 silica by SEM,and the essence was agglomeration of fused primary particles. It was indicated from situ FTIR studies that the inner SiOSi configuration of the silica particles changed leading to enhancement of crystallinity. [WT5HZ]
出处
《化学反应工程与工艺》
CAS
CSCD
北大核心
2000年第3期233-238,共6页
Chemical Reaction Engineering and Technology
基金
国家自然科学基金!项目 (No.2 970 60 1 0 )
中国石化总公司基金!项目 (X5980 38)
关键词
聚烯烃
催化剂载体
硅胶热活化
局部烧结
polyolefin catalyst supports
silica's thermoactivation
local sintering
