VII. AROBIN PROCESS
The Arobin process is a method of manufacture of aromatics from the high boiling residues of the DHD (dehydrogenation of naphthenes) and the HF (hydroforming) processes. The available charge stock consisted of about 5% residues from the distillation. The process was developed to the pilot plant stage only, with a catalyst volume of 25 cubic ft., and a charge rate of 120 gallons hour.
The following details of the process as applied to HF Plant residues were secured from Dr. Herold of Leuna, who is in charge of development work on further utilization of products from existing processes.
Charge to Arobin Plant
Bottoms from HF process charging mixed Rumanian and Hungarian straight run gasoline:
|
API Gravity |
21.2 |
|
|
Engler Distillation |
||
| IBP |
316° F. |
|
| 50% |
383 |
|
| E.P. |
676 |
|
|
Bromine No. |
14.4 |
|
|
Aromatics & Olefins |
98.5% |
|
|
Pour Point |
-66° F. |
|
|
Elementary Analysis: |
||
| Carbon |
90.59% |
|
| Hydrogen |
9.42 |
|
| Sulphur |
0.08 |
|
Operating Conditions
|
Catalyst Temperature (According to Catalyst activity) |
752-852° F |
|
Space velocity (liquid) |
0.65 vol. oil/vol. catalyst/hr |
|
Gasoline concentration at |
50% (by volume) |
|
Pressure |
2,940 psi |
|
Circulating gas |
1000-5000 volumes/volume gasoline/hour, to control the heat of reaction (about 0.360 BTU/lb charge) |
|
Chemical consumption of hydrogen |
5.45-6.20 cubic ft./lb of finished gasoline. |
|
Catalyst -KK catalyst + 1% MoO3 |
|
|
The MoO3 acts as a hydrogenation catalyst and thus prevents the formation of polymers which would cause coking. |
|
Yield and Quality of the Product
|
Average Net Yield |
Weight % |
|
| Methane |
0.2 |
|
| Ethane |
1.7 |
|
| Propane |
4.8 |
|
| Isobutane |
3.8 |
|
| N-Butane |
2.4 |
|
| Gasoline |
85.7 |
|
| TOTAL |
98.6 |
|
Quality of the Finished Product (Arobin)
|
API Gravity |
43.2 |
|
|
Octane No. (Method Method) |
86 |
|
|
+4.55 cc/gal TEL |
93.5 |
|
|
Bromine No. |
0.84 |
|
|
Reid Vapour Pressure |
5.9 |
|
|
Corrosion |
Neg. |
|
|
Freezing Point |
Below -76° F. |
|
|
Gum (Glass dish) |
4.0 mg/100 cc |
|
|
Aniline Point |
Below -4° F. |
|
|
Aromatics & Olefins |
65.0 vol. % |
|
|
Naphthenes |
27.0 |
|
|
Paraffins |
8.0 |
|
|
Elemetary Analysis |
||
| Carbon |
88.50% |
|
| Hydrogen |
11.45 |
|
|
Engler Distillation |
|
|
IBP |
117° F. |
|
7.0% at |
176 |
|
20.0 |
212 |
|
41.0 |
248 |
|
72.0 |
284 |
|
95.0 |
320 |
|
99.0 |
333 |
|
Residue |
0.8% |
Preparation of the Arobin Catalyst
1. Preparation of alumina. Commercial alumina is dissolved in hot 25% caustic solution, to give about 1.66 lbs. Al2O3/gallon. This solution is add 45% nitric acid to give a pH of 6. Precipitation temperature not over 122° F. After precipitation, the solution is filtered or decanted the precipitate is washed with pure water until the effluent shows no nitrate, and dried at 248° F, until the ash content is about 70%.
2. Preparation of silica gel. Waterglass solution (Sp. g. 1,333, SiO2 27%) and 10% sulphuric acid are reacted at 50-59° F. to give 3-4 pH. On heating 158-176° F, the clear sol congeals. This gel is broken into 1ź-2 pieces and washed until the wash water shows no trace of sulphate. The gel is dried at 248° F to an ash content of about 70%. It is pulverized in a mill (Wibratom) until at least 90% of the powder will pass a 10,000 mesh (per unit) sieve.
3. Preparation of the KK Catalyst from the gel. The alumina is kneaded in a kneading machine with enough water to make a plastic mass. A 45% nitric acid solution is added, the quantity being 10% of the theoretically needed to for aluminium nitrate. Then the powdered silica gel is added with continuous kneading to give a ratio Al2O3: SiO2=1:9. The mass if further kneaded for 6 to 10 hours. The mass is then extruded for feed to an adjoining candy manufacturing machine (Franconia), where it is formed into spheres.
4. Preparation of the Arobin Catalyst. The above spheres are soaked with ammonium molybdate solution made up in such proportions that one weight per cent MoO3 is absorbed. The spheres absorb practically all the liquid. They are then drained and dried at 356° F.
A 5-pound sample of this Arobin catalyst was secured for further testing.