A process to manufacture granular activated carbon from asphalt and sulfur has been developed in the fundamental study as well as in the bench scale batch system work.
This process consists of the following four steps:
1. Vulcanization: Asphalt such as vacum residue reacts with elemental sulfur to form a non-fusible intermediate.
2. Pelleting: Vulcanized product is crushed and extruded to cylindrical pellets. The propane deasphalted residue is used as a binder.
3. Carbonization: The pellets are carbonized in the oxidative atmosphere containing oxygen to improve the mechanical strength of activated carbon.
4. Activation: The carbonized pellets are activated with steam or carbon dioxide to prepare the granular activated carbon.
As the result, the quality of the activated carbon was comparable to a commercial market product and it was confirmed that it is possible to produce granular activated carbon by this new process on a commercial scale.

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The process preparing bead (spherical) activated carbon, to be used for fluidized bed adsorption such as waste water treatment, has been developed as a modification of the process previously reported in Part 1.
In the fundamental study, the following two processes have been developed:
1. Rolling Granulation System.
Asphalt such as vacuum residue reacts with elemental sulfur to form a partly-fusible intermediate, which is then crushed and heated in the rotary kiln to produce a bead product, and this product is carbonized and activated in an ordinary method.
2. Suspension Granulation System.
Asphalt such as vacuum residue reacts with elemental sulfur in aquous solution of PVA under high-speed agitation in an autoclave to form a bead product, and this product is carbonized and activated in an ordinary method.
It was found that the latter process was superior to the former one and the quality of the bead activated carbon was comparable to a commercial market product except for the apparent bulk density and the mechanical strength.

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In order to prepare the petroleum pitch for use as the blast furnace coke, pitches were produced from Gach Saran and Murban vacuum residue by heat-treatment at 425-440°C. The pitch thus obtained was fractionated by n-pentane, benzene and quinoline into four fractions; PS, PI•BS, BI•QS and QI, and the relationship between the amount of fractions in the pitch and the caking capacity of pitch was investigated. The caking capacity of the pitch was evaluated by a caking index determined by the Roga test.
It was found that there exists a clear relationship between the amount of fractions in the pitch and the Roga index when the pitches were classified into two groups corresponding to the amount of QI. A boundary value of QI was about 25%. When the amount of QI was 25% and below, the Roga index linearly increased with an increase in the amount of PI, and when the amount of QI was greater than 25%, the Roga index mainly depended on the amount of QI. That is, when the amount of QI was 25 and 50%, the Roga index was nearly constant, however when the amount of QI was greater than 50%, the Roga index decreased rapidly as the amount of QI increased. Further, the relationship between the amount of middle fractions (PI•BS+BI•QS) and the Roga index was shown in two separate curves and the turning point corresponded to the maximum value of middle fractions (_??_70%) in the course of heat-treatment and also to the boundary value of QI (_??_25%).

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The chemical structure and the caking capacity of fractions in the pitches prepared from Murban vacuum residue were investigated. The pitch was fractionated by n-pentane, benzene and quinoline into four fractions of PS, PI•BS, BI•QS and QI. The NMR spectra, molecular weight and elementary analysis were measured on the fractions, and the structural parameters were estimated. The caking capacity for each fraction was measured by means of the Roga test.
The following results were obtained.
(1) The structural parameters, molecular weight and the Roga index of each fraction were changing in the early stage of heat-treatment when the decomposition reaction mainly occurred, however these values became nearly constant in the latter stage when the polymerization-condensation reaction became predominant.
(2) The degree of condensation was considered to have a tendency to increase in the order of PS, PI•BS, BI•QS, QI. An average number of condensed aromatic rings of each fraction was estimated to be PS: 2-3, PI•BS: 6-7 and BI•QS: 11 and over, respectively. The Roga index of each fraction was PS: 11-22, PI•BS: 60-80, BI•QS: 74-90 and QI: 0, respectively. These results suggest that to obtain the pitch of high caking capacity, vacuum residue must be converted at least into the PI•BS fraction having 6-7 condensed aromatic rings and the aromaticity above 0.7.
(3) QI which has no caking capacity by itself showed a high caking capacity when coexisting with the fraction of high fluidity such as PS, PI•BS and BI•QS.

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The chemical structure of vanadyl complexes contained in petroleum heavy oils and the structural change of the chelate complexes during the carbonization process were investigated from ESR spectral parameters. Most of vanadyl porphyrin complexes occurring in original residues from Gach Saran crude oil and Athabasca tar sand bitumen were found to convert at the temperature ranging from 410 to 510°C, in to the new vanadyl complexes, to which the four donor atoms of the ligands are to be sulfur and nitrogen. The produced complex is considered to be one of the intermediates produced during the thermal decomposition of the vanadyl porphyrin complexes in the residues.
The addition of alkali metals (Li, Na, K) accelerates the formation of the intermediate complexes. It can be explained in terms of the formation of the activated compounds such as electron donor-acceptor complexes. The measurement of vanadium content in the benzene extract from Gach Saran residue treated with the alkali metals shows that the intermediate complexes were decomposed to vanadium oxide during the extraction process.

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