Catalyst – solid sorbent – or support therefor: product or process – Zeolite or clay – including gallium analogs – And additional al or si containing component
Reexamination Certificate
2000-03-10
2004-10-12
Elve, M. Alexandra (Department: 1725)
Catalyst, solid sorbent, or support therefor: product or process
Zeolite or clay, including gallium analogs
And additional al or si containing component
C502S064000, C502S070000, C502S074000
Reexamination Certificate
active
06803337
ABSTRACT:
The present invention relates to a catalytic composition which comprises a beta zeolite, a metal of group VIII, a metal of group VIB and optionally one or more oxides as carrier. The catalytic system of the present invention can be used for the hydrotreating of hydrocarbon mixtures and more specifically for the upgrading of hydrocarbon mixtures which boil within the naphtha range, containing sulfur impurities, i.e. in the hydrodesulfuration with contemporaneous skeleton isomerization and a reduced hydrogenation degree of the olefins contained in said hydrocarbons, the whole process being carried out in a single step. This catalytic system can be used, in particular, for the upgrading of mixtures of hydrocarbons which boil within the naphtha range deriving from cracking processes, preferably mixtures of hydrocarbons having a boiling point within the naphtha range deriving from FCC catalytic cracking (Fluid Catalytic Cracking).
Hydrocarbons which boil within the naphtha range deriving from FCC (i.e. gasoline cut) are used as blending component of gasolines. For this purpose, it is necessary for them to have a high octane number together with a low sulfur content, to conform with the law restrictions which are becoming more and more severe, in order to reduce the emission of contaminants. The sulfur present in gasoline mixtures in fact mainly comes (>90%) from the gasoline cut deriving from FCC.
This cut is also rich in olefins which have a high octane number. Hydrogenation processes used for desulfuration also hydrogenate the olefins present with a consequent considerable reduction in the octane number (RON and MON). The necessity has therefore been felt for finding a catalytic system which decreases the sulfur content in hydrocarbon mixtures which boil within the naphtha range and, at the same time, minimizes the octane loss (RON and MON), which can be achieved, for example, by the skeleton isomerization of the olefins present and/or by inhibiting the hydrogenation of the olefinic double bond.
The use of zeolites with a medium pore dimension as isomerization catalysts and the consequent recovery of octane in the charges already subjected to desulfuration are already known (U.S. Pat. No. 5,298,150, U.S. Pat. No. 5,320,742, U.S. Pat. No. 5,326,462, U.S. Pat. No. 5,318,690, U.S. Pat. No. 5,360,532, U.S. Pat. No. 5,500,108, U.S. Pat. No. 5,510,016, U.S. Pat. No. 5,554,274, U.S. Pat. No. 599,439). In these known processes, in order to obtain hydrodesulfuration with a reduced octane loss, it is necessary to operate in two steps, using in the first step catalysts suitable for desulfuration and in the second step catalysts for recovering the octane number.
U.S. Pat. No. 5,378,352 describes a process in a single step for desulfurating hydrocarbon fractions, with boiling points within the range of gasolines, using a catalyst which comprises a metal of group VIII, a metal of group VI, a zeolite selected from ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-50, MCM-22 and mordenite, and a metal oxide as ligand, with a process temperature preferably higher than 340° C.
Some catalytic materials containing metals of group VIII and group VIB, a refractory carrier and a zeolite selected from ZSM-35, ZSM-5, mordenite and fujasite, are described in EP 442159, EP 437877, EP 434123 for the isomerization and disproportioning of olefins; in U.S. Pat. No. 4,343,692 for hydrodewaxing; in U.S. Pat. No. 4,519,900 for hydrodenitrogenation, in EP 072220 for a process in two steps comprising dewaxing and hydrodesulfuration; in U.S. Pat. No. 4,959,140 for a hydrocracking process in two steps.
We have now surprisingly found a new catalytic system which can be used for the hydrotreating of hydrocarbon mixtures and, more specifically, we have found a catalytic system with which it is possible to desulfurate, with high conversion values, mixtures of hydrocarbons that boil within the naphtha range containing sulfur and olefins and contemporaneously obtain the skeleton isomerization of the olefins present with a low hydrogenation degree of the olefinic double bond. This new catalytic system is also active at temperatures and pressures that are lower than those preferably used in the known art for desulfuration.
Both skeleton isomerization and reduced olefinic hydrogenation enable hydrocarbon mixtures to be obtained, which boil within the naphtha range with very low RON (research octane number) and MON (motor octane number) losses.
The catalytic compositions of the present invention can not only be used for the desulfuration of hydrocarbon cuts that boil within the “heavy naphtha” range (130°-250° C.), i.e. cuts poor in olefins, but also feeds of “full range naphtha”, which boil within the range of 35°-250° C., i.e. in the case of cuts rich in olefins. In fact, the catalytic system of the present invention has a high selectivity for desulfuration with respect to hydrogenation, which represents an additional advantage in terms of octane recovery in the end-gasoline.
A first object of the present invention therefore relates to a catalytic composition which comprises a beta zeolite, a metal of group VIII, a metal of group VIB, and optionally one or more oxides as carrier.
Beta zeolite is a porous crystalline material described in U.S. Pat. No. 3,308,069, having a molar composition of oxides corresponding to the following formula:
[(
x
)
M
(1±0.1
−x
)
Q
]AlO
2
*y
SiO
2
*w
H
2
O
wherein x is less than 1, preferably less than 0.75, y varies within the range of 5 to 100, w varies within the range of 0 to 4, M is a metal selected from metals of groups IA, IIA, IIIA, or is a transition metal, n is the valence of M and Q is a hydrogen ion, ammonium ion, an organic cation or a mixture of these. Preferably y is greater than 5 and less than 50.
According to a particularly preferred aspect of the present invention the beta zeolite is in acid form i.e. in the form in which the cationic sites of the zeolite are prevalently occupied by hydrogen ions. It is especially preferable for at least 80% of the cationic sites to be occupied by hydrogen ions.
According to an aspect of the present invention, when the catalytic composition comprises beta zeolite and metals of group VIII and group VIB, said zeolite is preferably present in a quantity ranging from 70 to 90%; when the catalytic composition also comprises one or more oxides as carrier, said zeolite is preferably present in a quantity ranging from 5 to 30% by weight with respect to the total weight of the catalyst.
The catalysts used in the present invention preferably contain Cobalt or Nickel as metal of group VIII, whereas the metal of group VIB is preferably selected from molybdenum or tungsten. According to a particularly preferred aspect, Co and Mo are used. The weight percentage of the metal of group VIII preferably varies from 1 to 10% with respect to the total weight of the catalyst, even more preferably from 2 to 6%; the weight percentage of the metal of group VIB preferably varies from 4 to 20% with respect to the total weight of the catalyst, even more preferably from 7 to 13%. The weight percentages of the metal of group VIB and the metal of group VIII refer to the content of metals expressed as metal element of group VIB and metal element of group VIII; in the end-catalyst the metals of group VIB and VIII are in the form of oxides. According to a particularly preferred aspect, the molar ratio between the metal of Group VIII and the metal of group VIB is less than or equal to 2, preferably less than or equal to 1.
The oxide used as carrier is preferably the oxide of an element Z selected from silicon, aluminum, titanium, zirconium and mixtures of these. The carrier of the catalytic composition can consist of one or more oxides and the oxide used is preferably alumina or alumina mixed with an oxide selected from silica and zirconia.
The catalytic compositions of the present invention can be prepared with traditional methods, for example by impregnation of the beta zeolite with a solution containing a salt of a metal of group VIB and a salt o
Arrigoni Virginio
Ferrari Marco
Zanibelli Laura
Agip Petroli S.p.A.
Elve M. Alexandra
Ildebrando Christina
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