Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Halogenous component
Reexamination Certificate
2001-11-28
2002-08-13
Anthony, Joseph D. (Department: 1714)
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Halogenous component
C423S24000R, C423S213200, C423S481000, C252S190000, C210S683000
Reexamination Certificate
active
06432374
ABSTRACT:
TECHNICAL FIELD
This invention relates to a technique of removing chloride from fluids in various industries, particularly to an absorbent for effectively removing chlorides from a flow of hydrocarbon such as a catalytically reformed gasoline, a catalytically reformed gas or the like.
BACKGROUND ART
The chloride contained in petroleum base hydrocarbon is derived from a crude oil or through a catalytic reaction. Further, it is known that the chloride exists in the form of an inorganic chloride or an organic chloride. The inorganic or organic chlorides derived from the crude oil are contained in a straight-run naphtha or the like, and come out in succeeding stages. Such a chloride causes a problem such as corrosion of apparatuses in a downstream or the like.
On the other hand, a catalytic reforming catalyst for manufacturing a gasoline base material from a heavy naphtha is activated by means of the organic chloride. Therefore, if such a catalyst is used, a hydrogen chloride is produced by the decomposition of the organic chloride in a reaction process and released, and then discharged with a product from a reactor. Particularly when a deteriorated catalyst is regenerated by means of chloride, considerably high concentrations of the hydrogen chloride and the organic chloride are discharged outside of the reactor. And also, in a moving bed type catalytic reforming process separately having a reaction step and a regenerating step, a catalyst regenerated by an oxichlorination brings chlorine into the reaction step, so that the hydrogen chloride and the organic chloride are generated in the reactor and then discharged with a product outside of the reactor.
Among such chlorides, the hydrogen chloride is generally removed by means of an alkaline absorbent or an alkaline cleaning agent. As an example of solid absorbent in JP-B-52-35036 is described an absorbent obtained by adding a clay mineral as an inert binder to zinc oxide and calcium oxide as an absorbing ingredient. JP-A-7-506048 teaches a method of absorbing chloride in hydrocarbon by means of an active alumina carrying an alkaline metal thereon. Further, in order to prevent corrosion of the apparatus, in JP-A-7-88315 is described an example in which an absorbent layer is placed just after a catalyst layer. The absorbent in the example is made by carrying an oxide such as calcium oxide, sodium oxide or the like, as not readily releasing an absorbed hydrogen chloride, on a refractory oxide such as zeorite or the like.
Such an absorbent can effectively absorb the inorganic chloride just after being charged, but many absorbents are apt to lack an absorbing capacity during use in an industrial scale. Particularly, the absorbent containing an active alumina as a main ingredient thereof fastly absorbs and effectively operates at an early time on charging, but is small in an absorbing capacity. Further, in case of changing operation conditions, it has a problem of releasing the absorbed inorganic chloride such as hydrogen chloride or the like. Further, the organic chloride leaks therefrom from a considerably early time and there is a case that a concentration of the organic chloride becomes higher than that in the petroleum raw material, which is not well known to a person in the art. It is Considered that in a case of absorbing the chlorides by a physical absorption in a multiple component system, the organic chloride being weak in an absorbing power is purged by hydrochloric acid being strong in the absorbing power. A treating method by using an absorbent having the active alumina carrying the alkaline metal thereon or the like as a main ingredient can improve the absorbing capacity, but can not solve the problem of releasing the absorbed chloride.
On the other hand, the absorbent having zinc oxide and calcium oxide as described in JP-B-52-35036 is slightly inferior to the active alumina in an absorbing rate, but it is superior in that it has a high theoretical absorbing capacity and does not readily release the absorbed hydrogen chloride or the like due to absorption by chemical bond. However, in an actual device, the absorbent may come to be exchanged when only several percentage of the theoretical absorbing amount is reached. This is because calcium chloride or the like produced by reacting with the chloride in the fluid to be treated is deliquesced with a trace of moisture contained in the hydrocarbon or the like, to extremely promote deterioration of strength of the absorbent, so that the absorbent becomes powdery or soft during use. Therefore, a pressure loss thereon increases due to compacting of the absorbent itself and clogging of a subsequent strainer, catalyst layer or the like. Particularly, the absorbent becomes extremely powdery or soft when it is used at about normal temperature or under a condition of a relatively high content of the moisture.
DISCLOSURE OF INVENTION
It is, therefore, an object of the invention to provide an absorbent having the aforementioned zinc oxide as a main ingredient without extremely deteriorating its strength due to deliquescence with moisture in a crude petroleum, or causing the absorbent itself to be compacted or a subsequent strainer, a catalyst layer or the like to be clogged due to powdering or softening. When the object is attained, the absorbent can absorb chlorides in a crude petroleum over a long time and never releases them, so that troubles caused by corrosion by chloride can be largely decreased.
In order to solve the above object, the inventors experimentally made and studied zinc oxide base absorbents having various compositions. As a result, it is found that calcium oxide as alkaline ingredient does not function effectively, though it is so far considered to be essential in order to effectively absorb chlorides. As a result of a further study, it is found that even when compounded with a porous refractory inorganic material instead of a calcium oxide ingredient, an absorbing property for chloride per unit weight does not decrease and fracture of the absorbent and reduction in its strength hardly occur due to moisture in the crude petroleum, and the invention is accomplished.
That is, the above object can be attained by using an absorbent comprising 2-15 parts by weight of an inert binder and 5-25 parts by weight of a porous refractory inorganic carrier, based on 10 parts by weight of zinc oxide. As the absorbent contains the porous refractory inorganic material, it has pores of a macro size with a pore volume of 0.35-0.65 cm
3
/g of as measured by means of a mercury press-in method.
A solid chloride absorbent according to the invention is adopted to remove chlorides such as hydrogen chloride generated in a petroleum fraction treating processes using a catalyst activated by chloride or the like and to remove chlorides derived from crude oil. In the above processes using the activated catalyst are included a catalytic reforming process for naphtha fraction, a catalyst regenerating process such as oxichlorination in a moving bed type catalytic reforming process, a pretreatment process such as catalyst drying, hydrogen reduction or the like, a reaction process such as aromatization, and the like. As a petroleum fraction, heavy naphtha, light naphtha and the like may be mentioned. As a catalyst activated by means of chloride, mention may be made of a catalyst for manufacturing gasoline base material by catalytically reforming the above heavy naphtha, a catalyst for manufacturing benzene from the light naphtha, a catalyst for manufacturing BTX from the heavy naphtha and the like. As a concrete example of such a catalyst, mention may be made of ordinary catalytic reforming catalyst, a catalyst having noble metals in the 8th to 10th columns on a periodic table carried by various kind of zeolite, and the like.
The absorbent according to the invention comprises zinc oxide, the inert binder and the porous refractory inorganic material. The porous refractory inorganic material necessarily has many pores of a macro size in its structure, for example, kieselguhr, porous silica, porous alumi
Fujiwara Kaoru
Hayashi Nobuyashi
Ohashi Mitsuhiro
Shioya Yasushi
Takase Tsuneyoshi
Anthony Joseph D.
Süd-Chemie Catalysts Japan, Inc.
Sughrue & Mion, PLLC
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