Dehydration-hydrolysis processes and catalysts therefor
View Patent ↗Process for the co-production of acetic acid and dimethyl ether by contacting methyl acetate and methanol in the presence of a catalyst containing a crystalline zeolite having a FER framework type. The zeolite has crystallites having a dimension of about 500 nm or less in the c-axis.
1. A process for the co-production of acetic acid and dimethyl ether comprising the step of contacting methyl acetate and methanol in the presence of a catalyst comprising a crystalline zeolite having a FER framework type wherein said zeolite has crystallites having a dimension of about 500 nm or less in the c-axis, the ratio of the dimension in the c-axis to the dimension in the b-axis is less than or equal to 3:1 and 1 mol % to 60 mol % of its cation-exchange capacity is occupied by cations of an alkali metal, said alkali metal being cesium.
2. The process according to claim 1 wherein the crystallites have the dimension in the c-axis of about 350 nm or less.
3. The process according to claim 2 wherein the crystallites have the dimension in the c-axis of about 250 nm or less.
4. The process according to claim 3 wherein at least 70% of the crystallites have the dimension in the c-axis of about 250 nm or less.
5. The process according to claim 1 wherein the zeolite has a mesopore volume of at least 0.1 cm 3 /g as measured by N 2 absorption.
6. The process according to claim 5 wherein the mesopore volume is 0.1 to 0.2 cm 3 /g as measured by N 2 absorption.
7. The process according to claim 1 wherein the zeolite is ferrierite.
8. The process according to claim 1 wherein the catalyst contains a refractory oxide binder.
9. The process according to claim 1 wherein water is added to the process in an amount in the range from 0.1 to 60 mol % based on the total feed to the process.
10. The process according to claim 1 wherein the process is operated in the vapour phase.
11. The process according to claim 1 wherein the process is carried out at temperatures of from 170° C. to 300° C.
12. The process according to claim 1 wherein the process is carried out at pressures in the range from atmospheric pressure to 30 barg.
13. The process according to claim 1 wherein the zeolite is prepared by forming an aqueous synthesis mixture of silica, alumina, alkali metal and a saturated nitrogen-containing heterocyclic compound and heating said mixture under stirred conditions until the aluminosilicate zeolite crystallizes.