Modeling and approval of vinyl acetate synthesis process from acetylene

EXPERIMENTAL PART
Methodology for determining the activity and stability of catalysts. Catalytic activity was measured in a flow isothermal reactor with a catalyst bed of 6 cm3 volume and 7.5 cm height. Acetic acid was dispensed through a vaporizer with a medical dispenser. Experiments were conducted at 160, 180, 200℃ at acetic acid conversion levels not higher than 50%. The velocity of the mixture of gases is 722 cm-1. The ratio S2N2 : SN3SOON ≈ 6:1. The activity of the catalyst was calculated according to the following formula:
а = С_ВАm/V_k∙τ (г/л∙соат)

where: SVA is the % mass content of vinyl acetate in the sample.
m is the mass of the sample, g. Vk is the volume of the catalyst, l. t – sample analysis time interval, hours.
After 8-10 cycles, the stability of the catalysts was observed in the cyclic change of the synthesis temperature of 160-180-200℃. At each temperature, the process was carried out in stationary mode for 1.5 hours. Chromatographic analysis was used to quantify the products of the reaction. The material balance was released with an accuracy of 3-5%.
The temperature resistance of the catalysts was studied in a quartz flow reactor at temperatures of 160, 170, 180 and 200℃ for 8 hours at each temperature. Gas injection rate is 720±10 hour-1 and S2N2:SN3SOON =8:1.


EXPERIMENTAL RESULTS AND THEIR DISCUSSION
The average performance was taken as the acceptance criterion (the total work of the catalyst in terms of activity). The criterion has the following form:


Then, tts is the total cycle time (including the catalyst overload);
tp-catalyst working time;
to-catalyst overload time;
Movement of the wo-reaction mixture.
The peculiarity of the selected criterion is that it allows taking into account the technological features of the process, first of all, the effect of the rectification unit. The criterion reflects the dependence of the properties of this node (energy costs, vinyl acetate loss from the final level. The expression coefficients for the criterion are determined by the technical and economic indicators of existing networks.
As a second possible criterion for acceptance, the performance characteristic of the average complete cycle time:

The optimization objective reduces to finding the experimental functional I or I2 depending on several unknown functions.



But due to technological reasons, restrictions are imposed:
Т≤230⁰С; W₀≤W_onp., then
W0-the maximum permissible speed of the reaction mixture. Optimization of processes is carried out on the basis of a kinetic model. The system of differential equations in our example looks like this:

With boundary conditions