Catalyst, method of preparation thereof, and a hexane isomer production process

FIELD: industrial organic synthesis catalysts.

SUBSTANCE: invention relates to environmentally friendly processes for production of isoalkanes via gas-phase skeletal isomerization of linear alkanes in presence of catalyst. Invention provides catalyst for production of hexane isomers through skeletal isomerization of n-hexane, which catalyst contains sulfurized zirconium-aluminum dioxide supplemented by platinum and has concentration of Lewis acid sites on its surface 220-250 μmole/g. Catalyst is prepared by precipitation of combined zirconium-aluminum hydroxide from zirconium and aluminum nitrates followed by deposition of sulfate and calcination in air flow before further treatment with platinum salts. Hexane isomer production process in presence of above-defined cat is also described.

EFFECT: increased catalyst activity.

5 cl, 2 tbl, 6 ex

 

The invention relates to environmentally friendly methods of producing isoalkanes by skeletal isomerization of linear alkanes in the gas phase in the presence of a catalyst and may find application in the chemical and petrochemical industries.

One of the most promising processes increase the octane number motor fuels - isomerization of light gasoline, allowing linear hydrocarbon, C5-C8low octane (OC 0-62) to obtain branched isomers with OC 92-105. The share of isomerization processes in Russia is 0.2%, whereas in the United States of 5.6%. Due to limitations of the content of aromatic compounds in gasoline growth isomerization products into marketable fuels in developed countries it is planned to increase to 15%.

The most promising technologies isomerization of paraffins are design firms UOP (USA) and IFP (France), which are used organochlorine compounds [Bloomerg, Latrobe, W-Feoli, Rmatthews, Further development of technology isomerization of paraffins. Refining and petrochemicals, 4 (2001) 15]. Organochlorine compounds when released into the atmosphere lead to the formation of dioxins, substances in 105times more toxic than hydrogen cyanide, can accumulate and cause human cancer education [Vstation, Nature, 2000, No. 2].

Search IVF is logicheskie pure ways of conducting the process of isomerization of light gasoline, without the use of Halogens, is carried out in several directions. Widely investigated catalysts based on metal oxides, treated with different acid groups: sulfates [K.Arata, H.Matsuhashi, M.Hino, H.Nakamura, Synthesis of solid superacids and their activityes for reactions of alkanes, Catal. Today 81 (2003) 17. T.Lei, J.S.Xu, W.M.Hua, Z.Gao, New solid superacid catalysts for n-butane isomerization: Al2About3or SiO2supported sulfated zirconia, Appl. Catal. A:General 192 (2000) 181]; wolframite [S.Kuba, P.Lukinskas, R.K.Grasselli, B.C.Gates, H.Knozinger, J.Catal. 216 (2003) 353], and catalysts on the basis of salts of heteropolyacids [N.Essayem, G.Coudurier, M.Fournier and Vedrine, Acidic and catalytic properties of CsxH3-xPW12O40heteropolyacid compounds, Catal. Lett., 34 (1995) 223; N.Essayem, S.Kieger, G.Coudurier and Vedrine, Comparison of the reactivities of H3PW12O40and H3SiW12O40and their K+, NH4+and Cs+salts in liquid phase isobtane/butene alcylation.. Stud. Sur. Sci. Catal. 101 (1996) 591].

Catalysts based on sulfated Zirconia embedded in the industry [T.Kimura, Development of Pt/SO42-/ZrO2catalyst for isomerization of light naphtha, Catal. Today 81 (2003) 57, S.A.Gembicki, New Solid Acid Based Breakthrough Technologies, Stud. Sur. Sci. Catal., 130 (2000) 147]. Due to the high demand for isomers to obtain high-octane gasoline, the search for new more active isomerization catalysts continuously [U.S. Pat. US 5036035, B 01 J 27/053, C 07 C 2/54, 30.07.1991; US 6495733, B 01 J 27/053, 07 5/13, 17.12.2002; US 6448198, B 01 J 27/053, 10.09.2002; US 5629257, B 01 J 27/053, 13.5.1997; US 6706659, C 07 C 5/22, B 01 J 23/00, 13.03.2003].

It is known that the main parameter characterizing the activity supercolony catalysts in the isomerization reactions of alkanes, is the concentration of Lewis sites acid sites [J. van Gestel, V.T.Nghiem, D.Guillaume, J.P.Gilson, J.C.Duchet, J.Catal. 212 (2002) 173, J.C.Duchet, D.Guillaume, A.Monnier, C.Dujardin, J.P.Gilson, J. van Gestel, G.Szabo, P.Nascimento, J.Catal. 198 (2001) 328]. Catalysts have been developed based on sulfated zirconium dioxide with a concentration of Lewis sites of acid centers in the range of 90-120 mmol/g: D.J.Rosenberg and J.A.Anderson, On determination of acid site densities on sulfated oxides, Catal. Lett. 83 (2002) 59-90 µmol/g; E.A.Paukshtis, V.K.Duplyakin, V.P.Finevich, A.V.Lavrenov, V.L.Kirillov, L.I.Kuznetsova, V.A.Likholobov, B.S.Bal'zhmimaev, Stud. Sur. Sci. Catal., 130 (2000) 2543, - 100 µmol/g

The closest technical solution to offer is a sulfated Zirconia catalyst with a concentration of Lewis sites of acid centers 121 µmol/g [L.Zanibelli, A.Carati, C.Flego, R.Millini, New onestep synthesis of supported sulfated zirconia, Stud. Sur. Sci. Catal., 143 (2002) 813]. The catalyst is a sulfated zirconium dioxide with the addition of platinum, the content of the sulfur oxide is 5.1 wt.%, platinum, 0.3 wt.%. The catalyst was prepared in one stage by Sol-gel technology by mixing zirconium compounds Zr(OC3H7)4and hydroxide of tetrapropylammonium in propyl within 2 h, then added to the mixture of sulfuric acid and continue to mix 4 is at room temperature and 4 hours at a temperature of 60° C, the sample was then dried and calcined at 550°C for 5 hours On the calcined sample is applied platinum, dried and calcined at 550°C.

The disadvantage of this catalyst is the low concentration of Lewis sites of acid centers (121 μmol) and, consequently, its low activity in the reaction of skeletal isomerization of alkanes, which leads to the lack of efficiency of process of isomerization of hexane without the use of halogen in the catalyst composition.

The problem solved by this invention is the development of a new catalytic system based on sulfated Zirconia having high catalytic activity in the process of skeletal isomerization of hexane, which increases the efficiency of the process of isomerization of hexane on the catalysts that do not contain Halogens.

The task is solved by a catalyst of the process of obtaining isohexane by isomerization of normal hexane at a temperature of 180-230°S, which represents the sulfate deposited on the zirconium oxide with additives of aluminum oxide and platinum. The content of sulfate in the catalyst is from 3.0 to 9.0 wt.%, aluminum oxide of 2.5-3.0 wt.%, platinum 0.3 to 0.6 wt.%., ZrO287.5MHz-94,2.

The task is also solved by a method of obtaining the above catalyst. The catalyst was prepared drawing on the capacity of sulphuric acid, or salts with the nuclear biological chemical (NBC acid on joint hydroxide of zirconium-aluminum, precipitated from solutions of nitrate salts with ammonia at pH 11-11,5. After applying the sample is dried and calcined at a temperature of 630-660°, then enter the platinum by drawing on the capacity of hexachloroplatinic acid. The dried sample annealed up to 500°C for 3 h, tabletirujut and milled. The fraction of catalyst (0.5-1 mm is loaded into the reactor. The surface of the samples is 100-120 m2/year

The task is also solved by a method of producing isohexanol by isomerization of normal hexane in the gas phase at a temperature of 180-230°C, the pressure of 1-30 ATM in the presence of a catalyst comprising a sulfate deposited on the zirconium oxide with additives of aluminum oxide and platinum. The content of sulfate in the catalyst is from 3.0 to 9.0 wt.%, aluminum oxide of 2.5-3.0 wt.%, platinum 0.3 to 0.6 wt.%.

A distinctive feature of the proposed method isomerization of hexane is use the new supercyclone catalyst based on sulfated Zirconia with additives of aluminum oxide and platinum, the concentration of Lewis sites acid sites on the catalyst surface is 220 to 250 µmol·, the Content of sulfate in the catalyst is from 3.0 to 9.0 wt.%, aluminum oxide of 2.5-3.0 wt.%, platinum 0.3 to 0.6 wt.%, ZrO287.5MHz-94,2.

To determine the acid characteristics of the IR catalyst surface using low temperature adsorption of molecules of the probe. The powder catalyst was pressed into tablets weighing 15-20 mg/cm2and for thin tablets samples mixed with BaF2. Before adsorption, the samples restored with hydrogen at 200°With vacuum at the same temperature, then cooled to -173°and using the proportioning valve to produce a pumping cell in small doses. IR spectra were recorded on a Fourier spectrometer Shimadzu FTER-8300 with a resolution of 4 cm-1the number of scans 100. The concentration of the centers of adsorption is measured from the intensity of the absorption bands of adsorbed CO by the formula N=A/ρA0where: ρ - the weight of the tablet in g/cm2,the integral absorption coefficient equal to 0.8 cm/µmol for strip 2200-2190 cm-1characterizing Lisovskii acid centers, 2,6 - for strip 2175-2160 cm-1characterizing pentecosta acid sites.

The process of isomerization of hexane proceeds according to the following reactions:

n-C6 to normal-hexane:6H14;

2MP - methylpentan: CH3-CH(CH3)-CH2-CH2-CH3;

3MP - methylpentan: CH3-CH2-CH(CH3)-CH2-CH3;

2,3 DMB - 2,dimethylbutan: CH3-CH(CH3)-CH2(CH3)-CH3;

2,2 DMB - 2,dimethylbutan: CH3-(CH3)C(CH3)-CH2 -CH3.

The activity of the catalyst and the efficiency of the isomerization process as a whole is characterized by two rate constants of reactions:

- K1the reaction rate constant of isomerization of hexane in the mixture of isomers 2MP+3MP+2,CMB;

- K2the reaction rate constant of isomerization of the mixture of isomers 2MP+3MP+2,CMB in the target product 2.2 dimethylbutan.

The invention is illustrated by the following examples.

Example 1. The process of isomerization of normal hexane is as follows: hexane and hydrogen in the ratio of N2:hexane=2,1 passed through the catalyst bed at a pressure of 3 ATM and a temperature of 200°C. the reaction Products are condensed at the outlet of the reactor. The feed rate of hexane is 4.7 h-1the conversion of hexane equal to 65%.

The process is performed on the catalyst comprising a sulfate deposited on the zirconium oxide with additives of aluminum oxide and platinum. The composition of the catalyst are shown in table 1. The catalyst was prepared by deposition of sulfuric acid and platinum joint hydroxide of zirconium-aluminum deposited from solutions of nitrate salts with ammonia at pH 11. After application of sulphuric acid sample is dried, calcined in air flow at a temperature of 650°and introducing platinum by applying for capacity. The dried sample annealed at 500°during the course the e 3 h, tabletirujut and milled. The fraction of catalyst (0.5-1.0 mm is loaded into the reactor. The number of Lewis sites of acid centers on the surface of the catalyst and its activity in the reaction of isomerization of hexane are shown in tables 1, 2.

Example 2. Analogously to example 1, but the content of platinum is 0.6 wt.%.

Example 3. Analogously to example 1, but the pH of the joint deposition of zirconium hydroxide-aluminum is 11.5.

Example 4. Analogously to example 3, but the content of the sulfate is 9.0 wt.%, and aluminum oxide 2.9 wt.%.

These examples demonstrate methods of making catalysts, and high activity of the proposed catalysts in the process of skeletal isomerization of hexane, the concentration of Lewis sites of acid centers supercolony catalysts that do not contain Halogens, increases more than 2 times in comparison with the known method. The use of the catalysts increases the rate constants for the skeletal isomerization of hexane 4 (constant total isomerization of hexane) and 2.3 times (constant obtain the target product - 2.2 Dimethylbutane).

Table 1

The catalyst composition, the pH of the deposition and concentration of Lewis sites and pentecosta centers on sulfated Zirconia catalysts
ExamplesThe catalyst composition, wt.%pHN mkmol/g LCCN mkmol/g BKC
10,3Pt/SO42-/Al2O3/ZrO2< / br>
SO42-=6%; Al2O3=2,5A
11220130
20,6Pt/SO42-/Al2O3/ZrO2< / br>
SO4=6%; Al2O3=2,5%
11220150
30,3Pt/SO42-/Al2O3/ZrO2< / br>
SO42-=6%; Al2O3=2,5%
11,5240150
40,3Pt/SO42-/Al2O3/ZrO2< / br>
SO42-=9%; Al2O3=2,9%
11,5250170
5*0,3Pt/SO42-/Al2O3/ZrO2< / br>
SO4=6%; Al2O3=2,5%
10150140
6*0,3Pt2-/SO42-/Al2O3/ZrO2< / br>
SO42-=6%; Al2O3=2,5%
7,05085

140
The placeholder0,3Pt/SO42-/ZrO2< / br>
SO42-=5,1%
12137
* Examples illustrating the test outside of the proposed conditions

Table 2

The rate constants of reactions of isomerization of hexane
ExampleCatalystConstant 1-1The constant 2, p-1
10,3Pt/SO42-/Al2O3/ZrO20,810of 0.066
20,6Pt/SO42-/Al2O3/ZrO20,8500,065
30,3Pt/SO42-/Al2O3/ZrO20,9170,070
40,3Pt/SO42-/Al2O3/ZrO20,9090,073
5*0,3Pt/SO42-/Al2O3/ZrO20,2240,033
6*0,3Pt/SO42-/Al2O3/ZrO20,1030,011
The placeholder0,3Pt/SO42-/ZrO20,2030,027
* P is emery, illustrating the test outside of the proposed conditions

1. Catalyst to obtain isomers of hexane by skeletal isomerization of normal hexane-containing sulfated Zirconia with the addition of platinum, wherein the catalyst additionally contains aluminum oxide, the concentration of Lewis sites of acid centers on the surface is 220 to 250 µmol per gram and it is obtained by joint deposition of zirconium hydroxide-aluminum from nitric acid salts of zirconium and aluminum at pH 11,0-11,5, followed by the application of sulfate and calcining in a stream of air at a temperature of 630-660°and processing the salts of platinum.

2. The catalyst according to claim 1, characterized in that the content of components in the catalyst is, wt.%: Pt 0,3-0,6; SO42-3,0-9,0; Al2O32,5-2,9; ZrO287.5MHz-94,2.

3. The method of preparation of the catalyst obtain isomers of hexane by skeletal isomerization of normal hexane based on sulfated Zirconia with the addition of platinum, characterized in that it is produced by the joint deposition of zirconium hydroxide-aluminum from nitric acid salts of zirconium and aluminum at pH 11,0-11,5, followed by the application of sulfate and calcining in a stream of air at a temperature of 630-660°s, then the catalyst is treated with salts cards the us.

4. The method of obtaining isomers of hexane by skeletal isomerization of hexane in the gas phase in the presence of an acid catalyst containing sulfated zirconium dioxide with the addition of platinum, characterized in that the use of the catalyst according to claims 1 and 2.

5. The method according to claim 4, characterized in that the process is carried out at a temperature of 180-230°and the pressure of 1-30 ATM.



 

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