Xylene isomerization is a reaction

Xylene isomerization is a reaction of the type A $ B. In this case,
reaction cannot occur near the extract point if high purity is
required, otherwise the reverse reaction will pollute the product
and purity will always be below 99%. To overcome this situation,
reactors are inserted between the adsorption columns far from
the extract point [9,10]. However, since the minimum concentration
required in the extract for this new configuration is about
70 wt%, a much simpler configuration can be employed. Keeping
the catalyst and adsorbent mixed inside the columns, it may produce
a high enough p-xylene concentration stream to be further
processed by the crystallization unit. This approach involves simpler
operation and allows the direct contact between catalyst
and adsorbent resulting in more efficient p-xylene withdraw as it
is formed to overcome the thermodynamic equilibrium
constraints.
One of the most employed SMB based technologies for p-xylene
separation is UOP’s Parex. The studied aromatic complex uses this
technology consisting of 24 adsorbent beds with length and diameter
of 1.14 and 4.12 m respectively, p-diethylbenzene as desorbent,
particle diameter of 0.062 cm, and a time switch of
1.15 min [3]. The SMBR unit will keep the geometric characteristics
of the Parex unit, i.e. 24 adsorbent beds, with the possibility to
modify the location of inlets and outlets in order to use the appropriate
number of columns in each zone since column configuration
plays an important role when dealing with different product concentrations
[11]. Moreover, p-diethylbenzene cannot be used since
it isomerizes into o-diethylbenzene and m-diethylbenzene over
acid catalysts; toluene, which has been used in the industry, is
used as desorbent [10].

結果 (中文) 3:

二甲苯异构化是类型一美元在这种情况下的反应，
反应不能发生，提取高纯度的
点附近，如果需要，否则逆反应会污染产品
和纯度都会低于99%。为了克服这种情况，
反应堆插入吸附柱之间远远
提取点[9,10]。然而，由于最小浓度
要求在提取新配置是
70重量%，更简单的配置就可以使用。保持
催化剂和吸附剂混合在列，有可能产生
足够高的对二甲苯浓度流进一步
由结晶单元处理。这种方法包括简单的
操作和允许之间的催化剂
直接接触从而更有效的对二甲苯吸附剂退出这
形成克服热力学平衡
约束之一。
对二甲苯分离
最常用的基于SMB技术UOP Parex。研究芳香复杂使用这个
技术由24个吸附床的长度和直径1.14和4.12米的分别
，对二乙苯为脱附剂，
0.062厘米的粒径，和一个1.15分钟的3次
[开关]。膜生物反应器装置将保持的Parex单元的几何特性
，即24个吸附床，有可能
修改为入口和出口的位置，在每个区域使用适当的
列数自
列配置起着重要的作用，在处理不同的产品浓度
[ 11 ]。此外，对二乙苯不能自
异构为
酸催化剂用于甲苯，邻二和间二乙苯；已用于工业，是
作为解吸剂[ 10 ]。