Slurry Work at Fuel Research Board

The work on the slurry process has been done in the reactor shown in figure 2. In most instances, the temperature has been 265°C. and the pressure 20 atmospheres. Hall has also found that a flow rate of 2 cu. ft./hr. (at reaction conditions) is required to keep the catalyst in suspension in a tube having an internal diameter of 2 inches. This corresponds to a velocity based on the empty tube of 0.025 ft./second.

A comparison between the fixed bed and slurry operation with a synthetic ammonia catalyst is as follows:

	Fixed Bed	Slurry
SVH	500	110^1/
CO converted, %	92	92
CO à CO₂	9	8
CH4,g./m.³ fresh feed	29	19
Recycle ratio	2	2
Temperature, °C.	265	265
1/ Based on volume of slurry

The synthetic ammonia catalyst (7-14 mesh) used in the slurry was reduced in a fixed bed under standard conditions. It was then sealed in a ball mill and milled for 24 hours. The milled catalyst was washed out of the mill with Diesel oil fraction of an F.T. product and put into a reactor which contained wax (m.p. 90°C.) at 120°°C.

No special induction procedure is followed, and the catalyst is put into operation under the following conditions:

Gas	2H₂:1CO
Pressure	300 p.s.i.a.
Temperature, °C.	265
Conc. Catalyst	300 grams/liter
SVH based on volume of slurry	100
Recycle ratio	2.5:1
Conversion of CO	91%

The initial conversion of CO was 85%, increasing to 94% in 8 days. After about 70 days’ operation, the conversion under the foregoing conditions was 90 to 91%. The space velocity was increased to 200 V/V/hour and the CO conversion of 92% was obtained.

The most recent results on the slurry procecss obtained by Hall in work in progress during the latter part of July 1950 were as follows:

Catalyst	Synthetic ammonia
Pressure	300 p.s.i.a
Temperature, °C.	325
Slurry vehicle	Hard wax i.B.p. 450°C. m.p. 90°C.
Catalyst concentration	250-300grams/liter
SVH (based on slurry volume)	600
CO conversion	90%
C₁	20 g./m.³
C₂-C₄	68 g./m.³
C₅₊	74 g./m.³

Hall has studied catalyst concentrations ranging from 150 to 1000 grams/liter, and has found that the optimum concentration is approximately 250-300 grams/liter.

Hall’s results both with the slurry and the fluid bed have indicated that the space velocity based on the volume of the slurry or the volume of the expanded catalyst bed (in the fluidized process) have greater significance than the volume of gas per unit weight of iron per hour.

Hall has found that it is impossible to resuspend a settled catalyst. If the flow is interrupted for any reason, the insulation is stripped from the reactor so that the wax will solidify and keep the catalyst suspended.