CN1094787C - Process for preparing WOx-ZrO2 catalyst of super-strong acid - Google Patents

Abstract

The present invention relates to a simple method for preparing a novel WOx-ZrO2 super acidic catalyst, which specifically comprises: amorphous ZrO(OH)<x> and H2WO4 are mechanically and uniformly mixed and then are roasted at the high temperature of 800 to 825 DEG C. The catalyst comprises the compositions of the weight ratio: 0.3 to 0.6% of Pt, 75 to 95% of ZrO2 and 5 to 25% of WO<x>, wherein the weight ratio of ZrO2 to WO<x> is from 4 to 20: 1. The catalyst has high isomerization selectivity and high activity in n-C7 hydrotransform reaction at the temperature from 200 to 400 DEG C.

Description

A kind of WO x-ZrO 2The preparation method of super acidic catalyst

The invention belongs to a kind of simple novel WO _x-ZrO ₂The preparation method of super acidic catalyst is specifically with H ₂WO ₄Obtain with amorphous ZrO (OH) x high-temperature roasting after simple and mechanical the mixing.

WO _x-ZrO ₂Super acidic catalyst is the low temp isomerizing catalyst of developing in recent years of a kind of good lighter hydrocarbons.In recent years; along with to the sustainable growth of high-knock rating gasoline demand with to the pay attention to day by day of environmental protection; isoparaffin has become more and more important gasoline antiknock component, and the reaction of acid catalyzed alkane isomerization is added the important reaction of component as synthetic high-knock rating gasoline and is subjected to extensively attracting attention.At present, to light paraffins (C ₄-C ₆) existing extensive studies of isomerization and the industrialized unit that turns round of success, but for C ₇And the alkane (C of longer carbochain ₇ ⁺), because of its isomers is easy to cracking and high-octane rating multibranched paraffin (containing quaternary carbon) is less, application is restricted.So in actual applications, the application that makes isomerization process of cracking reaction is limited in C ₄-C ₆On the hydrocarbon.

At present, alkane isomerization and alkylation process all use liquid acid (H ₂SO ₄, HF, AlCl ₃) or the metal oxide (Cl-AlO of halogen modification ₃), its disadvantage is a contaminated environment not only, and etching apparatus.SO _X-/ ZrO ₂Catalyst is because to C ₇ ⁺The isomerization of paraffins selectivity is low, less stable, and meeting forms shortcomings such as sublimed sulfur compound in catalysis and regeneration, has limited its application in isomerization process.WO _x-Ji material is the new more promising solid acid that forms of a class.M.Scheithauer has reported a kind of WO at J.Catal.1998 in 180:1 one literary composition _x-ZrO ₂Super acidic catalyst preparation method: the hydration ZrO that the precipitation method are prepared ₂With ammonium metatungstate at the 383K 16h that refluxes, behind the transpiring moisture, in the dry 12h of 383K, at 773-1098K roasting 3h, preparation process is quite complicated at last.Hino and Arata be at J.Chem.Soc .Chem.Commun.1998, the WO that reports in 18:1259 one literary composition _x-ZrO ₂The preparation method of super acidic catalyst is fairly simple, but also is to adopt the ammonium metatungstate solution infusion process.

The object of the present invention is to provide a kind of simple novel WO _x-ZrO ₂The preparation method of super acidic catalyst.

The present invention adopts mechanical mixing to prepare WO _x-ZrO ₂The super acids carrier is immersed in precious metals pt on this super acids carrier again.

Catalyst of the present invention is formed weight ratio:

Pt 0.3-0.6 ZrO ₂ 75-95 WO _x 5-25

ZrO in the above-mentioned catalyst ₂: WO _xWeight ratio be 4-20: 1.

WO of the present invention _x-ZrO ₂The preparation method of super acidic catalyst:

(1) at first adopt the precipitation method to prepare amorphous ZrO (OH) x;

(2) press ZrO ₂: WO _xWeight ratio is 4-20: 1 ratio is with ZrO (OH) x and H ₂WO ₄Mechanical mixture is even, 800-825 ℃ of roasting 3h;

(3) the product of roasting compression molding is used H ₂PtCl ₆Solution impregnation, dried overnight in 500-525 ℃ of roasting 5h, makes required Pt/WO again _x-ZrO ₂Catalyst, the weight ratio that this catalyst is formed is: Pt 0.3-0.6, ZrO ₂75-79, WOx 5-25.

The present invention and existing WO _x-ZrO ₂Method for preparing catalyst is compared, and has following characteristics:

(1) preparation method is simple, and after a need mechanical mixture was even, high-temperature roasting got final product.

(2) prepared catalyst is in 200-400 ℃ of scope, to n-C ₇The isomerization selectivity of facing the hydrogen conversion reaction is all more than 80%.

Embodiments of the invention are as follows:

Embodiment 1

Get 65g ZrOCl ₂8H ₂O is dissolved in the 500ml water, is made into the solution of 0.4M, drips NH under 35-40 ℃ of intense agitation ₃H ₂O, the PH=10-11 of control solution, after precipitation left standstill aging 4h, filtration, washing, dried overnight obtained amorphous ZrO (OH) x.Take by weighing 3.44gZrO (OH) x and 0.49g H respectively ₂WO ₄, after mechanical mixture is even,, obtain WO through 800-825 ℃ of roasting 3h _x-ZrO ₂Catalyst.With 3g WO _x-ZrO ₂Catalyst is at the H of 1.2ml ₂PtCl ₆Solution (1gH ₂PtCl ₆6H ₂O/50ml water) dipping 24h in, dried overnight in 500-525 ℃ of roasting 5h, makes catalyst A, and the composition weight ratio of this catalyst is: Pt 0.3, ZrO ₂85, WO _x15.

Embodiment 2

The preparation method of amorphous ZrO (OH) x is with embodiment 1.Take by weighing 3.44g ZrO (OH) x and 0.16g H respectively ₂WO ₄, after mechanical mixture is even,, obtain WO through 800-825 ℃ of roasting 3h _x-ZrO ₂Catalyst.With 3g WO _x-ZrO ₂Catalyst is at the H of 2.4ml ₂PtCl ₆Flood 24h in the solution, dried overnight in 500-525 ℃ of roasting 5h, makes catalyst B, and the composition weight ratio of this catalyst is: Pt 0.6, ZrO ₂95, WO _x5.

Embodiment 3

The preparation method of amorphous ZrO (OH) x is with embodiment 1.Take by weighing 3.44g ZrO (OH) x and 0.81g H respectively ₂WO ₄, after mechanical mixture is even,, obtain WO through 800-825 ℃ of roasting 3h _x-ZrO ₂Catalyst.With 3g WO _x-ZrO ₂Catalyst is at the H of 1.2ml ₂PtCl ₆Flood 24h in the solution, dried overnight in 500-525 ℃ of roasting 5h, makes catalyst C, and the composition weight ratio of this catalyst is: Pt 0.3, ZrO ₂75, WO _x25.

The evaluating catalyst that each embodiment makes:

Make raw material with normal heptane, the weight (hourly) space velocity (WHSV) (WHSV) of micro-amounts of liquids pump feed liquor is 2ml/g.h, H ₂/ n-C ₇=15: 1 (mol).Use air at 450 ℃ of preliminary treatment 1.5h before the reaction earlier, face hydrogen and be warming up to 470 ℃, behind the reductase 12 h, the sample introduction reaction.Product ov-101 capillary chromatographic column on-line analysis, fid detector, sample analysis behind the reaction 8min.

Catalyst	Reaction temperature (℃)	C 7Conversion ratio (%)	Selectivity of product (%)
						Isomerized products	Pyrolysis product	The aromatization product
			A	280	16.28				93.39	2.28	4.33
320	44.3	88.85				7.81	3.34
				400	48.69			81.44	12.24	6.32
B	280	10.0				93.94	1.28				4.78
			320	26.04	92.87			2.75	4.38
	400	40.69				86.16	5.81			8.03
			C	280	17.37			95.01	2.84		2.15
320	27.45	93.29				2.91	3.8
				400	43.88			81.12	12.63	6.25

Evaluation shows, the catalyst activity height that method for making of the present invention makes, and the isomerization selectivity is good.

Claims (1)

1. WO _x-ZrO ₂The preparation method of super acidic catalyst is characterized in that step is as follows:

(1) at first adopt the precipitation method to prepare amorphous ZrO (OH) x;

(2) press ZrO ₂: WO _xWeight ratio is 4-20: 1 ratio is with ZrO (OH) x and H ₂WO ₄Mechanical mixture is even, 800-825 ℃ of roasting 3h;

(3) the product of roasting compression molding is used H ₂PtCl ₆Solution impregnation, dried overnight in 500-525 ℃ of roasting 5h, makes required Pt/WO again _x-ZrO ₂Catalyst, the weight ratio that this catalyst is formed is: Pt 0.3-0.6, ZrO2 75-79, Wox 5-25.