CATALYST FOR HYDROCRACKING AND A METHOD FOR PRODUCING GAS OIL WITH LOW POUR POINT

Abstract: The invention relates to a new catalyst applicable in hydrocracking of hydrocarbons. The catalyst according to the invention contains as catalytically active components: a) a ZSM-5 zeolite wherein 10-100 % of the exchangeable hydrogen ions have been replaced by nickel ions, and b) 0.3-3 parts by weight of magadiite in hydrogen form for 1 part by weight of component (a). The catalyst according to the invention can be applied to particular advantage in hydrodewaxing of gas oil, and enables one to produce gas oil with extremely low pour point.

Description: CATALYST FOR HYDROCRACKING AND A METHOD FOR PRODUCING GAS OIL WITH LOW POUR POINT The invention relates to a new catalyst applicable in hydrocracking of hydrocarbons. More particularly, the invention relates to a catalyst compris ¬ ing as active components ZSM-5 zeolite which has been subjected to ion ex ¬ change with nickel and magadiite in hydrogen form (further on: Ni-ZSM-5/H- -magadiite catalyst). This catalyst can be applied to particular advantage in hydrodewaxing of gas oil, and possesses high selectivity and a long life time The invention also relates to a method for producing arctic gas oil (i.e gas oil with extremely low pour point) by subjecting gas oil to hydrodewaxing in the presence of the above catalyst. It has been known for a long time that pour point of gas oils can be lowered by reducing the amount of higher straight-chained and moderately branched - with only single methyl groups in side chains - paraffins (further on. n-paraffins) contained therein. One of the methods suitable for reducing the amount of n-paraffins in gas oils is cracking in the presence of hydrogen and a catalyst, i.e. catalytic hydrocracking (hydrodewaxing) of gas oils For this purpose those catalysts (so-called shape-selective catalysts) are partic ¬ ularly suitable which catalyse only the cracking of higher n-paraffins intended to be removed, but do not or only slightly catalyse the cracking of other com ¬ ponents (such as isoparaffins, lower hydrocarbons, etc ) Such shape-selective catalysts have been disclosed, inter alia, in US patents Nos 3,700,585 and 3,894,934. A very widely used representative of shape-selective catalysts is the commercially available ZSM-5 zeolite catalyst in hydrogen form (ZSM-5 or, according to a more accurate terminology, H-ZSM-5) Utiliz ¬ ing such catalysts, pour point of gas oils can be lowered typically to -5 to -25°C, depending on the pour point of the starting substance. Hydrogen gas present at cracking does not participate in the reaction, and its role is only to suppress further dehydrogenation of olefins with a single unsaturated bond, which are one of the primary products of cracking. This further dehydrogenation of olefins proceeds upon thermal effects, and leads to coke-formation on the catalyst, decreasing (in extreme cases even breaking down) thereby the activity of the catalyst. It is, however, obvious that further dehydrogenation of olefins with a single unsaturated bond can be suppressed only to an extent determined by the reaction equilibria under the prevailing conditions and by the law of mass action. A smaller fraction of olefins with a single unsaturated bond, which form as primary products in hydrocacking, consists of lower hydrocarbons which appear in gasoline (a twin product of hydrocracking). These compounds have a favourable influence on the quality of gasoline. However, the situation is different with higher olefins having a single unsaturated bond which appear in gas oil. Hydrogen present in the process only suppresses but does not prevent the thermal dehydrogenation of these latter olefins. A part of the resulting olefins with multiple unsaturated bonds adsorbs on the surface of the catalyst and gets coked there, whereas an other part of them gets stabilized by conversion into aromatics. The resulting aromatics decrease the cetane number of gas oil and lead to an increase in noise level when gas oil is used in engines. A method for suppressing these latter disadvantages has been disclosed in Hungarian patent No. 209,141. According to this method gas oil is subjected to hydrodewaxing in the presence of a catalyst comprising as active components ZSM-5 zeolite which has been subjected to ion exchange with nickel and magadiite which has been subjected to ion exchange with nickel (Ni-ZSM-5/Ni-magadiite catalyst). This catalyst is able to suppress the formation of aromatics from olefins with multiple unsaturated bonds, whereby both the decrease in cetane number and the increase in noise level upon use in engines can be suppressed considerably, without affecting, however, the level of n-paraffm removal and thereby the pour point of the resulting gas oil. However, with the increase of motorisation there is an increasing need for gas oils with extremely low pour point, typically about or below -50°C, the production of which has not yet been solved. Now we have found that when a catalyst comprising as active components ZSM-5 zeolite which has been subjected to ion exchange with nickel and magadiite in hydrogen form (i.e. Ni-ZSM-5/H-magadiite catalyst) is applied in the otherwise known catalytic hydrodewaxing of gas oil, a gas oil with extremely low pour point is obtained which can be safely used even under arctic conditions, without, however, affecting considerably either the cetane number of gas oil or the noise level when gas oil is used in an engine. Thus, the invention relates to a catalyst suitable for hydrocracking hydrocarbons, particularly for hydrodewaxing gas oils. The catalyst according to the invention comprises as active components (a) ZSM-5 zeolite which has been subjected to ion exchange with nickel (Ni-ZSM-5) and (b) magadiite in hydrogen form (H-magadiite). In Ni-ZSM-5, the one of the catalytically active components of the catalyst according to the invention, 10-100 %, preferably 30-100 %, more preferably 50-100 %, particularly preferably 80-100 % of the exchangeable hydrogen ions of ZSM-5 zeolite in hydrogen form (H-ZSM-5) have been replaced by nickel ions. The catalyst according to the invention comprises, for 1 part by weight of Ni-ZSM-5 with the above nickel replacement level, 0.3-3 parts by weight, preferably 0.5-2 parts by weight, particularly preferably 0.75-1.5 parts by weight of H-magadiite. The catalyst according to the invention may optionally also contain inert binders and/or auxiliary agents necessary for preparing a shaped catalyst. As binders and/or auxiliary agents any substance known to be applicable for this purpose can be used, examples of which are water glass, phosphates and hydrated aluminium oxides. The amount of binders and/or auxiliary agents may be 1-95 % by weight, usually 5-50 % by weight, preferably 10-30 % by weight, related to the total weight of the catalyst. It is, however, not absolutely necessary to use any binder or auxiliary agent, since the catalyst can also be applied as a powder mixture or in a form compressed without any binder. We have found that using the above catalyst a gas oil with much lower pour point than usual but at the same time with good cetane number and causing low noise level when used in an engine can be produced. This observation is very surprising from many respects. Although from Hungarian patent No. 209 141 , which discloses the use of a Ni-ZSM-5/Ni-magadiite catalyst, one could conclude that the presence of a magadiite component will suppress the cyclization of multiply unsaturated olefins, avoiding thereby a lowering in cetane number and an increase in noise level, but it could by no means be expected that the H-magadiite component will considerably increase the n-paraffin cracking activity of the catalyst, since when one proceeds as disclosed in Hungarian patent No. 209,141 , the n-paraffin content of the gas oil product (and its pour point closely connected therewith) is hardly changed as compared to that attainable by a method utilizing H- -ZSM-5 catalyst alone. From a combination of the teachings of Hungarian patent No. 209,141 and US patents Nos. 3,700,585 and 3,894,934 one skilled in the art could rather conclude that the magadiite component will suppress cyclization of multiply unsaturated olefins without, however, exerting any essential influence on the cracking of n-paraffins. Consequently, one could not expect that an arctic gas oil with a pour point of about -50°C will form. A likewise unexpected observation is that the catalyst according to the invention has a longer life time than the catalyst disclosed in Hungarian Patent No. 209,141. Taking into account that coke formation is caused by multiply unsaturated olefins, and the introduction of Ni ions assists their partial rehydrogenation, one had to expect that the catalyst according to the invention, in which only one of the components comprises Ni-ions, will be less able to eliminate the formation of coke-forming compounds. Our practical experiences are, however, fully contrasted with this expectation. Without wishing to bound the essence of the invention to theoretical considerations we assume that the favourable effects observed with the catalyst according to the invention (considerable increase in cracking of n-paraffins, prolonged life time of the catalyst) can be traced back to some specific favourable structural characteristics defined by the acidic centres of H-magadiite. Ni-MZS-5 zeolite, which is one of the active components of the catalyst according to the invention, can be prepared by a known ion exchange process from commercially available MZS-5 zeolite in H-form. Ion exchange can be performed e.g. as disclosed in Hungarian patent No. 209,141 . H-magadiite, the second active component of the catalyst according to the invention, is a commercially available material, which can also be prepared by known methods [see R.K. Her: J. Colloid Sci. 19, 648-657 (1964) and G. Lagaly et al.: Proc. Int. Clay Conf. Madrid, 1973, 663-673]. H-magadi- ite can also be prepared from magadiites with exchangeable cations other than hydrogen by a known ion exchange method (acidic treatment) The catalyst according to the invention can be prepared by simply admixing the two active components. However, when a shaped catalyst with appropriate deformation stability is required, the two active components are admixed with conventional binders and/or auxiliary agents, the resulting mixture is granulated, and the granules are dried, if necessary When used for hydrodewaxing of gas oil, the above catalyst is calcined first in a known way (e g as described in Hungarian patent No 209,141 ), and then it is subjected to heat treatment in hydrogen or in a hydrogen-containing gas mixture, such as in reforming gas This series of operation is termed here as "activation of the catalyst" Calcination is performed typically at 500-600°C for 1-3 hours Treatment with hydrogen is performed generally at a slightly lower temperature (e.g. at 400-550°C) for 1-3 hours. Gas oil is hydrodewaxed with the thus-activated catalyst under conditions disclosed in detail in the literature The operational parameters may be e.g the following reactor temperature 300-500°C spatial velocity (LHSV)- 1-2 h 1 gas/liquid ratio 500-1000 Nm 3 /m 3 pressure 30-50 bar The following non-limiting Examples serve to illustrate further details of the invention Example 1 Preparation of the catalyst 4300 g of Nι-ZSM-5, wherein 50 % of the exchangeable hydrogen ions had been replaced by nickel ions, 3200 g of H-magadiite, 4 2 litres of ethyl silicate (Sι0 2 content 31-32 %), 900 g of 65 w/w % H 3 P0 4 and 250 g of AI(OH) 3 were mixed, the resulting mass was granulated, and the granules were dried at 120°C Example 2 Hydrodewaxing of gas oil with the catalyst according to the invention Prior to use, 100 ml of the catalyst obtained according to Example 1 were calcined in the reactor at 550°C for 2 hours, and then a reforming gas with a hydrogen content of 80 v/v % was passed through the catalyst at a rate of 100 l/hour for 12 hours under a pressure of 40 bar Thereafter hydrodewaxing of a gas oil (a 1 1 v/v mixture of Russian heavy gas oil and vacuum gas oil, its characteristics are listed in Table 1 ) was started under the following conditions reactor temperature 340-430°C spatial velocity 1 5 h 1 gas/liquid ratio 700 Nm 3 /m 3 pressure 40 bar H 2 content of reform nng gas 80 v/v % The resulting product was distilled to remove gasoline fraction and the characteristics of the resulting gas oil were determined The results are given in Table 1 Example 3 Hydrodewaxing of gas oil with a comparative catalyst For comparison purposes the process described in Example 2 was repeated using a Nι-ZSM-5/Nι-magadιιte catalyst prepared according to Example 1 of Hungarian patent No 209,141 The results are given in Table 1 Table 1 Characteristics of the starting substance and of the hydrodewaxed gas oils Starting Hydrodewaxed Characteristics substance gas oil product Ex 2 Ex 3 Density, kg/m 867 887 877 Sulphur content, % 0,905 1,05 0,98 Nitrogen content, ppm 230 235 233 Basic nitrogen content ppm 129 138 134 Viscosity at 20°C, cSt 10,66 13,74 13,16 Pour point, °C (ASTM D 2500) 0 -52 -18 Cetane index 56 52 52 Flash point, °C 88 96 96 Saturated compounds, w/w % 63,4 56,3 5342 of them n-paraffins, w/w % 27 8,47 12,42 Aromatics, w/w % 36,60 43,70 4660 It appears from the data of Table 1 that when using the catalyst according to the invention a gas oil with extremely low pour point (-52°C), usable even under arctic conditions, can be obtained, whereas the pour point of the product obtained with the closest known catalyst is only -18°C At the same time the product obtained with the catalyst according to the invention retains the favourable properties of the product prepared according to the closest known solution its aromatics content and cetane index are essentially the same as those of the product obtained according to the comparative example When operating as described in Example 3, the activity of the catalyst decreased after 840 hours of operation to such an extent that refreshment was required (regeneration of the catalyst was, however, not yet necessary). Refreshment was performed by passing reforming gas through the catalyst for 12 hours at 500°C. In contrast, no refreshment of the catalyst according to the invention was required during the whole period of operation (1 100 hours); the activity of the catalyst remained practically unchanged at the end of the 1 100th hour. After 1 100 hours of operation the reaction according to Example 2 was stopped, the catalyst was removed from the reactor, and its coke content was determined. 4.4 w/w % of coke was deposited on the catalyst. As an information, in such reactions catalysts require regeneration generally when 12-14 w/w % of coke has been deposited thereon

Claims: What we claim is 1 A catalyst for hydrocracking of hydrocarbons, particularly for hydrodewaxing of gas oil, characterised in that it contains as catalytically active components (a) a ZSM-5 zeolite wherein 10-100 % of the exchangeable hydrogen ions have been replaced by nickel ions (Ni-ZSM-5), and (b) 0 3-3 parts by weight of magadiite in hydrogen form (H-magadnte) for 1 part by weight of Nι-ZSM-5 2 A catalyst as claimed in claim 1 , characterised in that it contains as component (a) a ZSM-5 zeolite wherein 50- 00 % of the exchangeable hydrogen ions have been replaced by nickel ions 3 A catalyst as claimed in claim 1 or 2, characterised in that it contains 0 i-2 parts by weight of H-magadnte for 1 part by weight of Nι-ZSM-5 4 A catalyst as claimed in any of claims 1 to 3, characterised in that it contains 0 75-1 5 parts by weight of H magadiite for 1 part by weight of Nι-ZSM-5 5 A catalyst as claimed in any of claims 1 to 4, characterised in that it contains over the catalytically active components one or more usual binder and/or auxiliary agent, too, in an amount of 1-95 w/w % for the total weight of the catalyst 6 A catalyst as claimed in claim 5, characterised in that it contains the bιnder(s) and/or auxiliary agent(s) in an amount of 5-50 w/w % for the total weight of the catalyst 7 A process for catalytic hydrodewaxing of gas oil, characterised in that the process is performed in the presence of a catalyst as claimed in any of claims 1-6

Inventors: BALAI MARIA, BEYER HERMANN, BORBELY GABRIELLA, CZAGLER ISTVAN, FEHER PAL, FORSTNER JANOS, GEORGIADES GABOR, GERGELY JANOS, HORVATH JOZSEF, JOVER BELA, KANTOR LASZLO, KOVACS IMRE, LENCSE ISTVAN, PERGER JOZSEF, PETRO JOZSEF, RATOSI ERNO, SZALMASNE PECSVARI Gabriella, SZIRMAI LASZLO, SZOLLOSI JOZSEF, ZSIDA LASZLO, BALAI, MARIA, BEYER, HERMANN, BORBELY, GABRIELLA, CZAGLER, ISTVAN, FEHER, PAL, FORSTNER, JANOS, GEORGIADES, GABOR, GERGELY, JANOS, HORVATH, JOZSEF, JOVER, BELA, KANTOR, LASZLO, KOVACS, IMRE, LENCSE, ISTVAN, PERGER, JOZSEF, PETRO, JOZSEF, RATOSI, ERNO, SZALMASNE PECSVARI, GABRIELLA, SZIRMAI, LASZLO, SZOLLOSI, JOZSEF, ZSIDA, LASZLO
Applicants: BALAI MARIA, BEYER HERMANN, BORBELY GABRIELLA, CZAGLER ISTVAN, FEHER PAL, FORSTNER JANOS, GEORGIADES GABOR, GERGELY JANOS, HORVATH JOZSEF, JOVER BELA, KANTOR LASZLO, KOVACS IMRE, LENCSE ISTVAN, MOL MAGYAR OLAJ & GAZIPARI RT, PERGER JOZSEF, PETRO JOZSEF, RATOSI ERNO, SZALMASNE PECSVARI Gabriella, SZIRMAI LASZLO, SZOLLOSI JOZSEF, ZSIDA LASZLO, BALAI, MARIA, BEYER, HERMANN, BORBELY, GABRIELLA, CZAGLER, ISTVAN, FEHER, PAL, FORSTNER, JANOS, GEORGIADES, GABOR, GERGELY, JANOS, HORVATH, JOZSEF, JOVER, BELA, KANTOR, LASZLO, KOVACS, IMRE, LENCSE, ISTVAN, MOL MAGYAR OLAJ-ES GAZIPARI RESZVENYTARSASAG, PERGER, JOZSEF, PETRO, JOZSEF, RATOSI, ERNO, SZALMASNE PECSVARI, GABRIELLA, SZIRMAI, LASZLO, SZOLLOSI, JOZSEF, ZSIDA, LASZLO
Application year: 1996
Main classification: B01J29
IPC codes: B01J29, C10G45, C10G47