Jianwei Li

Suspension catalytic distillation of simultaneous alkylation and transalkylation for producing cumene

This work deals with the improvement of the suspension catalytic distillation (SCD) process. An improved process that alkylation and transalkylation reactions for producing cumene are carried out simultaneously in a SCD column, was put forward. The kinetic data of alkylation of benzene with propylene over a modified β-zeolite catalyst, YSBH-01, were determined in a fixed-bed laboratory micro-reactor. On this basis, the equilibrium stage (EQ) model (MESHR equations) is established to simulate the SCD column. The performance of the SCD column is discussed. The innovation present in this work for the SCD process is also suitable for the fixed-bed catalytic distillation (FCD) process for producing cumene.

Azeotropic Distillation: A Review of Mathematical Models

Abstract Azeotropic distillation as an early and important special distillation process is commonly used in laboratory and industry. It can be used for separating the mixture with close boiling point or forming azeotrope. This paper tries to provide a review on azeotropic distillation for general readers, focusing on entrainer selection and mathematical models. Since the 1950s, along with extractive distillation, azeotropic distillation has gained a wide attention. Like extractive distillation, the entrainer, i.e., the third component added to the system, is also the core of azeotropic distillation. In the process design and synthesis, the graphical method (in most cases refer to as triangular diagram) is often employed. But it is better to take on the results from graphical method as the initial values of rigorous equilibrium (EQ) stage/non‐equilibrium (NEQ) stage models. One outstanding characteristic of the EQ/NEQ stage models different from extractive distillation and catalytic distillation is to describe phase split for heterogeneous azeotropic distillation. In general, the operation process is very sensitive to some parameters in the case of more than one azeotrope formed, and thus the phenomenon of multiple steady states (MSS) tends to appear.

Comments on special distillation processes

The purpose of this letter is to offer some comments regarding the topic of special distillation processes. Distillation, with its unique advantages in operation and control, becomes a very powerful separation tool in laboratory and industry. Although many promising separation methods are constantly put forward by engineers and scientists, most of them cannot become alternatives of distillation on a large product scale. Among all distillation processes, special distillation processes possess an important position. Herein, a new term, “special distillation processes,” is proposed, that is, the distillation processes by means of which the mixtures with close boiling point or forming an azeotrope can be separated into their pure constituents. The other distillation processes are, therefore, called ordinary distillation processes. We are interested in the field of special distillation processes, and have been working on them for many years [Lei et al., 2003, 2005; Li et al., 2005]. Table 1 gives a distribution of 20 articles except one comment [Lei et al., 2003] with respect to ordinary distillation and special distillation processes in the Korean Journal of Chemical Engineering from 1984 to 2005 (April) by the title “distillation” search. The parenthesis denotes the number of articles. It can be seen that except for only four articles [Assabumrungrat et al., 2004; Kim et al., 1996; Seo et al., 1999; Ko et al., 2002] with respect to special distillation processes, the others are concerned with ordinary distillation processes. However, the situation is different in the regional journal, AIChE Journal, where just in the year 2004 there are up to nine articles with respect to special distillation processes. We feel that the future research hotspot in the field of distillation may be the special distillation processes. Special distillation processes can be divided into two types: one with mass separating agent (i.e., the third component or solvent added) and the other without mass separating agent. The former involves azeotropic distillation (liquid solvent as the separating agent), extractive distillation (liquid Table 1. Article distribution among distillation processes

Improvement of separation process of synthesizing MIBK by the isopropanol one-step method

The separation process of synthesizing MIBK (methyl isobutyl ketone) by an isopropanol one-step method, in which the multi-component mixture contains AC (acetone), IPA (isopropanol), water, MIBK, MIBC (methyl isobutyl carbinol), DIBK (di-isobutyl ketone), etc., was studied. As a high-purity of MIBK over 99.5 wt% is required in industry, the development of an effective separation method is urgent. In this work, first, by means of VLE (vapor-liquid equilibrium) experiments and PROII simulation, the possible azeotropes formed in the investigated system were tested. Then, the separation process was simulated with the result that the calculated and designed values were in good agreement, which indicated that the calculated results were reliable. On this basis, the original separation process was improved. In the original separation process, the yield of MIBK for a concentration of MIBK over 99.5 wt% was small, only 32.5%. In the improved separation process (step two), two columns (one extractive distillation column and the other solvent recovery column) were added and some simplification was made so as to recycle MIBK. In this case the yield of MIBK was 91.7%. Moreover, about 27.6% water stream per kilogram MIBK product is saved.