CONTROL OF PHYSICAL STRUCTURE OF SILICA-ALUMINA CATALYST
CONTROL OF PHYSICAL STRUCTURE OF SILICA-ALUMINA CATALYST
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DOI：
10.1021/ie50516a029
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发表时间：
1952-01-01
影响因子：
--
通讯作者：
INNES, WB
中科院分区：
文献类型：
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作者：
ASHLEY, KD;INNES, WB
这就提出了开发一种适合于每天处理超过160吨凝胶状二氧化硅的方法的问题。旧的方法基于这样的概念，即硅胶必须用低温空气部分干燥，然后在施加铝之前洗涤除去钠，对于这样的大规模操作似乎是不切实际的。很快就确定，用大量的水洗涤水凝胶以除去钠将需要重新制浆操作，因为滤饼会破裂。进行这种操作的最经济的方法是在一系列真空转筒式旋转过滤机上洗涤，在每个过滤阶段之间对滤饼进行再制浆。这样做的尝试很快证明，通过在适度搅拌下混合酸和硅酸钠制备的凝胶浆料具有太宽的粒度范围。凝胶状物质很快会堵塞滤布，使凝胶无法在旋转过滤器上清洗。这个问题首先由一位作者（3）通过在酸和硅酸盐的混合过程中使用带筛网的叶轮搅拌器来解决，然后添加增粘剂（4）-即胶水或氢氧化铝。这得到了用于旋转过滤和洗涤的最佳粒度的凝胶浆料。氢氧化铝的疏水作用使得在过滤、洗涤或干燥水凝胶之前加入铝盐和氨似乎可以解决洗涤问题并大大简化操作。因此，在改变温度、浓度和温度的同时，
This presented the problem of developing a process suitable for the handling of over 160 tons per day of gelatinous silica. The old method, based on the concept that the silica gel had to be partly dried with low temperature air and then washed free of sodium before applying the aluminum, appeared impractical for such a large scale operation.It was soon established that washing the hydrogel with the large volume of water required to free it of sodium would require a reslurrying operation because of cracking of the filter cake. The most economical way of carrying out such an operation is to wash on a series of vacuum drum-type rotary filters with repulping of the cake between each stage of filtration. Attempts to do this soon demonstrated that the gel slurry prepared by mixing acid and sodium silicate with moderate agitation had too broad a range of particle size. The semicolloidalmaterial quickly blinded a filter cloth so that the gel could not be washed on a rotary filter. The problem was first solved by one of the authors (3) by use of a screen-shrouded impeller-agitator during the mixing of acid and silicate, followed byaddition of a flocculating agent (4)—ie, glue or aluminum hydroxide. This gave a gel slurry of optimum particle size for rotary filtration and washing. Theflocculating effect of aluminum hydroxide made it seem that addition of an aluminum salt and ammonia before filtering, washing, or drying the hydrogel would solve the washing problem and greatly sim-plify operations. Therefore, this procedure was tried while vary-ing temperature, concentra-