Hidrocloracion De Metanol

HYDROCHLORINATION OF METHANOL T O METHYL CHLORIDE IN FIXED CATALYST BEDS
M. S. T H Y A G A R A J A N , R A J I N D E R K U M A R , A N D N. R. K U L O O R Department of Chemical Engineering, Indian Institute of Science, Bangalore, India
The vapor phase hydrochlorination of methanol to methyl chloride in fixed beds with silica gel-alumina (88 to 12) and y-alumina catalysts was studied in a glasstubular reactor in the temperature range o 300" f to 390" C. Of the two catalysts studied, y-alumina gave nearly equilibrium conversions under the experimental conditions. The data are expressed in the form of second-order irreversible rate equations for both the catalysts studied.
CHLORIDE is an important starting material in the manufacture of silicone high polymers. Apart from this, it findsapplications in the low temperature polymerization of butyl rubbers and as intermediate in the manufacture of methylene chloride, which is extensively used in industry. The methods used for the production of methyl chloride are chlorination of methane and hydrochlorination of methanol ( 3 ) . The first method suffers from the disadvantage that it results in

METHYL

the formation of a group ofcompounds which have to be fractionated in order to obtain pure methyl chloride. Very little information is available on the hydrochlorination of methanol. The present investigation was undertaken to study the reaction in fixed beds of silica gel-alumina (88 to 12) and y-alumina catalysts.
Thermodynamic Considerations

The stoichiometric equation for the preparation of methyl chloride frommethanol and hydrogen chloride is given as CH3.OH

+ HC1

--t

CH3.Cl

+ H20

s

0

Figure 1.

1
~

The equilibrium constants a t various temperatures were evaluated from the available thermodynamic data (4). The equilibrium conversions were then evaluated from the equation
8 1 400 11
600
I

I

1

I

1
and are shown in Figure 1. The equilibrium conversion decreases from99% a t 300' K. to 85% a t 1000" K. T o produce

ZOO

e00

1000

TBHPERATURE, *K

Effect of t'emperature on equilibrium conversion

WATER

I

Figure 2.
1. 2.

Experimental setup
6.
Reactor

3. 4. 40.
5.

Constant overhead tank Aspirator bottle Hg manometer Methanol storage HCI generator Mixer

7. Thermocouple
8. Condensers 9. N a O H bubbler 10. Mariotte systemVOL. 5

NO. 3

JULY 1966

209

methyl chloride in high conversions and in reasonably high rates the temperature range of 600’ to 700’ K. is explored for kinetic studies.
/ A

Experimental

I I

Equipment a n d Operation. A flow diagram of the apparatus is shown in Figure 2 . The reactor is a borosilicate glass tube of 15-mm. i.d. and 700 mm. long. A thermowell is provided forinserting the calibrated iron-constantan thermocouple. Care is taken to keep the tip of the thermowell at the center of the catalyst bed when the catalyst is packed inside the reactor tube. The reactor is also packed with porcelain beads which serve as the preheater for the reactant gases and as a distributor. The reactor is provided with a radiation heater and the energy input to the heater is controlledby a Dimmerstat. Arrangements are made for the admission of the reactants a t the bottom of the reactor and for withdrawal of the products through a side tube a t the top. Reactants. METHANOL, analytical reagent grade, is metered through a calibrated all-glass rotameter and fed into the preheater. A steady feed rate is obtained by the pressure of air displaced by water from a constant-level tank.HYDROGEN CHLORIDE.An all-glass apparatus for the preparation of hydrogen chloride is a modified form of the apparatus developed by Bhatnagar and Kuloor ( Z ) , so that dry hydrogen chloride could be produced a t pressures slightly higher than atmospheric. The gas is dried by passing it through a calcium chloride tube and is metered using a calibrated glass capillary flowmeter. The manometric...