Mineral oils: processes and products – Chemical conversion of hydrocarbons – Plural serial stages of chemical conversion
Reexamination Certificate
2000-04-27
2004-09-28
Griffin, Walter D. (Department: 1764)
Mineral oils: processes and products
Chemical conversion of hydrocarbons
Plural serial stages of chemical conversion
C208S059000, C208S064000, C208S066000, C208S067000, C208S068000
Reexamination Certificate
active
06797153
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of hydrocracking heavy oils or extraheavy oils with the generation of coke being suppressed. More specifically, the present invention relates to a method of hydrocracking heavy oils or the like wherein the generation of coke is suppressed in the presence of pressurized hydrogen and a catalyst comprising active carbon having specific properties and comprising iron carried on the active carbon, and heavy metals such as Ni and V, asphaltene, residual carbon, sulfur, nitrogen and the like in the heavy oil or extraheavy oil, are removed by cracking and subjected to a heat treatment.
2. Description of the Related Art
Recently, as the world-wide trend in the petroleum refinery industry, the proportion in production of light-weight products is increasing. Accordingly, it is becoming more and more important, from the standpoint of effective utilization of resources, that heavy oils or extraheavy oils such as atmospheric distillation-residual oils, vacuum distillation-residual oils, catalytically cracked residual oils, oil sand oils and coal-liquefied oils and the like, which remain after removing valuable light-weight fractions, can be hydrocracked and further converted into useful intermediate fractions.
There have been a number of reports about the hydrocracking of heavy oils by using catalysts. As one example of upgrading heavy oils by using catalysts containing active carbon having specific properties with a metal carried thereon, U.S. Pat. No. 5,358,634 and U.S. Pat. No. 5,364,524 have been proposed.
In U.S. Pat. No. 5,358,634, a process of hydrocracking heavy hydrocarbon oils by using an active carbon catalyst having specific properties is disclosed. This is a method of cracking a heavy hydrocarbon oil which contains no less than 70% of a heavy oil content having a boiling point of not lower than 343° C. in a fixed-bed reactor. The reference suggests that, according to the method, under the existence of active carbon having at least 0.2 cc/g of pore volume and at least 50 m
2
/g of surface area of a pore distribution range of 10-40 nanometers, the average pore diameter being 4 to 5.4 nanometers, the heavy metal (Ni and V) removal rate is at least 59%, the desulfurization rate is at least 9.5%, the residual carbon decomposition rate is at least 13.5% and the removal rate of asphaltene defined as a content insoluble to pentane is at least 10%.
U.S. Pat. No. 5,364,524 discloses a process of hydrocracking a heavier oil. This is a method of hydrocracking a heavy hydrocarbon oil which contains no less than 97% of a heavy oil content having a boiling point of not lower than 343° C. in a fixed-bed reactor. The reference suggests that, according to the method, under the existence of a catalyst in which Mo (or W) and Co (or Ni) are carried on an active carbon carrier having properties including at least 0.2 cc/g of pore volume and at least 50 m
2
/g of surface has a pore distribution range of 10-40 nanometers, the average pore diameter being 4 to 6 nanometers, at least 23% of Ni and V can be removed.
These prior arts are clearly different from the present invention which will be described below, in terms of the properties of the catalyst, the types of metals carried on the catalyst, the type of the reactor, as well as the heavy metal removal rate and the residual carbon decomposition rate.
On the other hand, the applicant of the present invention has proposed in JP-A 6-165935 a method in which hydrocracking with a relatively small amount of hydrogen consumption is made possible by using, as the hydrocracking catalyst for heavy oils, a catalyst in which metal active components such as nickel and iron selected from group VIII in the periodic table are carried on active carbon produced from brown coal as a carrier. However, according to this method, as heavy oils are hydrocracked at only one stage in the process, it is difficult to reduce the amount to be used of the catalyst and suppress the generation of coke at a high conversion rate.
In addition, the applicant of the present invention has proposed in JP-A 9-235569 a method of hydrogenating heavy oils at two stages as one of the improved versions of the technique belonging to catalytic hydrocracking. In order to carry out the hydrocracking of heavy oils in two stages, this method comprises: a first step of adsorbing a coke precursor and coke into a coke adsorbent to remove them, the coke precursor and the coke being obtained by carrying out a thermal decomposition of the heavy oil under the existence of 2 to 10 wt. % of the coke adsorbent to the feedstock oil and hydrogen; and a second step of carrying out a thermal decomposition of the substantially whole amount of the thermally decomposed oil obtained by the first step from which the coke precursor and the coke have been removed, under the presence of hydrogen, iron compounds and active carbon having properties such as a MCH conversion rate of 45-85%, specific surface area of 800-1000 m
2
/g, pore volume of 0.7 to 1.4 cm
3
/g, mesopore (2-50 nanometers) volume of not less than 70% and average pore diameter of 3-6 nanometers. The coke adsorbent of the first step comprises: at least one carbon material selected from the group consisting of brown coal, brown coal char, petroleum cokes, active carbon, carbon black and graphite; and at least one member of iron compounds selected from the group consisting of iron sulfide, iron oxide and natural pyrite. At the first step, the carbon material and the iron compounds are present in a simply mixed state in the heavy oil. The iron compound of the second step includes at least one member of compounds selected from the group consisting of iron sulfide, iron oxide and natural pyrite. At the second step, the active carbon and the iron compounds in the thermally decomposed oil are present in a simply mixed state. However, in the method of simply mixing the carbon material and the iron compounds in the hydrogenation of heavy oils at two stages as disclosed in JP-A 9-235569, since the density of the carbon material and that of the iron compound differ from each other and, as the reaction proceeds, each density varies according to the amount of coke precipitated and heavy metals deposited on the carbon material and the iron compound, selection of the conditions in fluidization operation using gases and liquids for homogeneously dispersing the catalyst becomes complicated and difficult.
In the method in which the carbon material and the iron compounds are present in heavy oils in a simply mixed state, if the conditions in fluidization operation are selected such that the catalysts are homogeneously dispersed in the reactor, a suspension type or slurry bed may be selected and the catalysts flow out of the reactor with gases and cracked oils. In a case in which there is a preposition that catalysts are disposed of after use, such a suspension type may not be a problem. However, if re-use of the catalysts which still keeps a sufficient level of activity is intended, it is necessary to separate the catalysts which have flowed out of the reactor from the cracked oils and to recycle the separated catalysts to the reactor, which makes the process complicated.
In the RFCC processes for increasing production of the gasoline fraction and the process of hydrodesulfurizing feedstock to be supplied to the RFCC processes, when a feedstock which contains a relatively high amount of residual carbon content and metals such as Ni and V is supplied, some of the residual carbon and metals poison the catalyst and deterioration of the catalysts occurs, although the degree of the deterioration depends on the feedstock to be supplied. Conventionally, in hydrodesulfurizing, a step of removing Ni and V, in what is called a guard reactor, is provided prior to the hydrodesulfurization in order to reduce deterioration of the catalysts due to deposition of Ni and V and precipitation of coke on the catalysts. In the case of the catalyst used here, the pores of the alumina carrier are made larg
Fukuyama Hidetsugu
Ohtsuka Koji
Sawamoto Shuhei
Terai Satoshi
Arnold Jr. James
Flynn ,Thiel, Boutell & Tanis, P.C.
Griffin Walter D.
Petroleum Energy Center
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