CN104888781A - Preparation method of fluorination catalyst - Google Patents

Abstract

The invention discloses a preparation method of a fluorination catalyst. The preparation method is as follows: preparing a solution of active component metal salts, wherein preferably the atomic ratio of Co/Cr is 0.05-0.25 and the atomic ratio of Y/Cr is preferably 0.01-0.15; reacting with ammonia water as a precipitant at a PH value between 7 and 9; further stirring and aging for 9-11 minutes; filtering, and washing with deionized water till the solution is neutral; drying a filter cake at a temperature of 100-150 DEG C; carrying out calcination in an inertial gas environment to obtain a catalyst precursor; crushing the catalyst precursor and mixing the catalyst with graphite; laminating the uniformly mixed powder till the lamina cannot be crushed with hands; at the temperature of 200-400 DEG C, introducing inertial gas and hydrogen fluoride mixed gas, and carrying out fluorination to obtain the catalyst, wherein metal cobalt and yttrium form corresponding metal oxide during calcination stage; small metal oxide particles move in the catalyst precursor and the catalyst precursor is etched by the particles, the etching of the residual moisture in the catalyst precursor to the catalyst precursor can also be catalyzed, so as to form a series of porous structures in which medium pores take a great proportion.

Description

A kind of preparation method of fluorination catalyst

Technical field

The invention belongs to catalyst field, relate to the catalyst that a kind of gas phase fluorination prepares HFA 134a concretely.

Background technology

In recent years, CFCs is day by day serious to the destruction of ozone layer, and HFA 134a (HFC-134a) is a kind of colourless, nontoxic, incombustible chemical substance, and be a kind of HFC type cold-producing medium, ozone depletion latent energy value (ODP) value is zero.Thermodynamic property and the CFC-12 of HFC-134a are quite similar, safety can compare favourably with CFC-12, be acknowledged as the best substitute of CFC-12.

HFC-134a is generally prepared by trichloro-ethylene and anhydrous hydrogen fluoride, there are liquid phase method and vapor phase method two kinds of preparation methods at present.Liquid phase method generally adopts the halide of antimony as catalyst, but the method exists low conversion rate, and the shortcoming such as reactor corrosion condition is serious.The course of reaction that vapor phase method prepares HFC-134a is main in two steps: the first step, and trichloro-ethylene and hydrogen fluoride fluoridize synthesis 1,1,1-trifluoro-2-chloroethane (HCFC-133a); Second step, 1,1,1-trifluoro-2-chloroethane and hydrogen fluoride gas phase fluorination synthesize HFC-134a.Current gas phase process display, uses effective catalyst, conservative control reaction temperature, pressure, rate of charge, and the conversion ratio of first step reaction trichloro-ethylene can reach more than 90% substantially.But the reaction that HCFC-133a and hydrogen fluoride gas phase fluorination synthesize HFC-134a is the disadvantageous endothermic reaction on a thermodynamics, although HCFC-133a conversion ratio can be improved by improving reaction temperature, but temperature raises and causes catalyst coking to be accelerated, and shortens the service life of catalyst simultaneously.

The Xi'an patent No. in modern age 01141970.9 refer to a kind of method that Metal Substrate introducing two kinds coordinative roles except chromium base prepares fluorination catalyst.The feature of the method is that collaborative, auxiliary catalysis and suppression crystal formation produce the stability that improve catalyst precarsor to various metals base mutually, catalyst precarsor and catalyst are armorphous, extend the service life of catalyst, obtained catalyst precarsor specific area is greater than 200m ²/ g.

The Japan Showa electrician patent No. 94119527.9 refer to containing Ga, Cr, O and F catalyst as basic composition element, and its main feature is that the atomic ratio of Ga and Cr is in 0.0001 to 0.15, be preferably 0.003 to 0.05, the life-span of gained catalyst significantly improves than conventional chromium-based fluorination catalyst, and its specific area is also larger.

The great Jin patent No. 92104869.6 refer to a kind of method for preparing catalyst comprising amorphous chromium, and the feature of the method is fluorinated to Oil repellent to be at least 8(wt) %, specific area is at least 170m ²/ g.

More patent document all has the activity addressed higher specific area and be conducive to improving catalyst, but is showed no the research of the pore structure relevant to specific area.High-specific surface area greatly improves the contact area of catalyst and raw material, and rise in catalyst catalytic action to be mainly carried in these pore structures can with the active metal atom of contact raw.First the micropore depths of smaller aperture due is filled according to Polanyi-Dbinin potential energy theory metallic compound, along with micropore is constantly filled, hole depth shoals, and when arriving appropriate depth, will produce a large amount of nano level catalytic active center (being filled in the metallic element in hole).But not only relevant with micropore in the catalyst of Chemical Manufacture, central hole structure plays a key effect for catalyst activity, according to adsorption dynamics adsorption kinetics principle, mesopore plays conveying effect, dominate the speed of absorption, and preparation 1,1,1, the raw material trichloro-ethylene of 2-HFC-134a or 1,1,1-trifluoro-2-chloroethane are all the relatively large organic molecules of size, the aperture structure that mesopore is suitable for is conducive to the absorption to these molecules, improves reaction speed.

Summary of the invention

The object of the invention is the deficiency overcoming background technology, design a kind of catalyst of reasonable pore size distribution$, when not affecting its service life, there is higher catalytic activity.

The technical solution used in the present invention is:

A preparation method for fluorination catalyst, comprises the following steps:

Step 1: activity component metal salt is preferably according to Co/Cr the atomic ratio that 0.05 ~ 0.25, Y/Cr is preferably 0.01 ~ 0.15 and is mixed with solution;

Step 2: react as precipitating reagent using ammoniacal liquor, pH value controls between 7 ~ 9, and continues to stir aging 9 ~ 11min.Filter, and spend deionized water to neutral;

Step 3: dried at the temperature of 100 ~ 150 DEG C by filter cake, finally in inert gas environment, carries out roasting, prepares catalyst precursor at 150 ~ 350 DEG C of temperature;

Step 4: pulverized by catalyst precursor, and be mixed into the graphite of 2% ~ 4%, the pressed powder mixed to hand is pinched not broken, at the temperature of 200 ~ 400 DEG C, passes into inert gas and hydrofluoric gaseous mixture is fluoridized, prepares required catalyst.

Activity component metal salt in described step 1 is nitrate, villaumite or sulfate.

Advantage of the present invention is: metallic cobalt and yttrium itself exist certain catalytic activity and can control central hole structure generation in roasting process, corresponding metal oxide can be formed at firing stage, metal oxide granule moves in catalyst precarsor, catalyst precarsor is etched, and in energy catalysis catalyst precarsor, residual moisture etches catalyst precarsor, forms a series of pore structure accounting for larger proportion with mesopore.

Accompanying drawing explanation

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.

Fig. 1 is the pore structure table of catalyst precarsor in the present invention;

Fig. 2 is the conversion ratio table of 1,1,1-trifluoro-2-chloroethane in the present invention.

Detailed description of the invention

Embodiment 1

The slaine of cobalt and chromium is hybridly prepared into solution according to atomic ratio 0.05:1, precipitation reaction is carried out using ammoniacal liquor as precipitating reagent, PH is 7, and continue to stir aging 9min, then filter, and spend deionized water to neutral, filter cake is dried at the temperature of 110 DEG C, last in inert gas environment, roasting is carried out at 350 DEG C of temperature, prepare catalyst precursor, catalyst precursor is pulverized, and be mixed into the graphite of 2%, the pressed powder mixed to hand is pinched not broken, at the temperature of 200 DEG C, pass into inert gas and hydrofluoric gaseous mixture is fluoridized, prepare required catalyst.The pore structure of catalyst precarsor as shown in Figure 1.

Embodiment 2

The slaine of cobalt and chromium is hybridly prepared into solution according to atomic ratio 0.15:1, precipitation reaction is carried out using ammoniacal liquor as precipitating reagent, PH is 8, and continue to stir aging 10min, then filter, and spend deionized water to neutral, filter cake is dried at the temperature of 110 DEG C, last in inert gas environment, roasting is carried out at 350 DEG C of temperature, prepare catalyst precursor, catalyst precursor is pulverized, and be mixed into the graphite of 3%, the pressed powder mixed to hand is pinched not broken, at the temperature of 300 DEG C, pass into inert gas and hydrofluoric gaseous mixture is fluoridized, prepare required catalyst.The pore structure of catalyst precarsor as shown in Figure 1.

Embodiment 3

The slaine of cobalt and chromium is hybridly prepared into solution according to atomic ratio 0.25:1, precipitation reaction is carried out using ammoniacal liquor as precipitating reagent, PH is 9, and continue to stir aging 11min, then filter, and spend deionized water to neutral, filter cake is dried at the temperature of 110 DEG C, last in inert gas environment, roasting is carried out at 350 DEG C of temperature, prepare catalyst precursor, catalyst precursor is pulverized, and be mixed into the graphite of 4%, the pressed powder mixed to hand is pinched not broken, at the temperature of 400 DEG C, pass into inert gas and hydrofluoric gaseous mixture is fluoridized, prepare required catalyst.The pore structure of catalyst precarsor as shown in Figure 1.

Embodiment 4

The slaine of yttrium and chromium is hybridly prepared into solution according to atomic ratio 0.01:1, precipitation reaction is carried out using ammoniacal liquor as precipitating reagent, PH is 7, and continue to stir aging 10min, then filter, and spend deionized water to neutral, filter cake is dried at the temperature of 110 DEG C, last in inert gas environment, roasting is carried out at 350 DEG C of temperature, prepare catalyst precursor, catalyst precursor is pulverized, and be mixed into the graphite of 2%, the pressed powder mixed to hand is pinched not broken, at the temperature of 250 DEG C, pass into inert gas and hydrofluoric gaseous mixture is fluoridized, prepare required catalyst.The pore structure of catalyst precarsor as shown in Figure 1.

Embodiment 5

The slaine of yttrium and chromium is hybridly prepared into solution according to atomic ratio 0.05:1, precipitation reaction is carried out using ammoniacal liquor as precipitating reagent, PH is 8, and continue to stir aging 9min, then filter, and spend deionized water to neutral, filter cake is dried at the temperature of 110 DEG C, last in inert gas environment, roasting is carried out at 350 DEG C of temperature, prepare catalyst precursor, catalyst precursor is pulverized, and be mixed into the graphite of 3%, the pressed powder mixed to hand is pinched not broken, at the temperature of 350 DEG C, pass into inert gas and hydrofluoric gaseous mixture is fluoridized, prepare required catalyst.The pore structure of catalyst precarsor as shown in Figure 1.

Embodiment 6

The slaine of yttrium and chromium is hybridly prepared into solution according to atomic ratio 0.15:1, precipitation reaction is carried out using ammoniacal liquor as precipitating reagent, PH is 7, and continue to stir aging 11min, then filter, and spend deionized water to neutral, filter cake is dried at the temperature of 110 DEG C, last in inert gas environment, roasting is carried out at 350 DEG C of temperature, prepare catalyst precursor, catalyst precursor is pulverized, and be mixed into the graphite of 4%, the pressed powder mixed to hand is pinched not broken, at the temperature of 400 DEG C, pass into inert gas and hydrofluoric gaseous mixture is fluoridized, prepare required catalyst.The pore structure of catalyst precarsor as shown in Figure 1.

Embodiment 7

By cobalt, yttrium respectively with the slaine of chromium according to atomic ratio 0.15:1, 0.05:1 is hybridly prepared into solution, precipitation reaction is carried out using ammoniacal liquor as precipitating reagent, PH is 9, and continue to stir aging 9min, then filter, and spend deionized water to neutral, filter cake is dried at the temperature of 110 DEG C, last in inert gas environment, roasting is carried out at 350 DEG C of temperature, prepare catalyst precursor, catalyst precursor is pulverized, and be mixed into the graphite of 2%, the pressed powder mixed to hand is pinched not broken, at the temperature of 200 DEG C, pass into inert gas and hydrofluoric gaseous mixture is fluoridized, prepare required catalyst.The pore structure of catalyst precarsor as shown in Figure 1.

Embodiment 8

Catalyst obtained by embodiment 1 ~ 7 is respectively used to 1,1,1-trifluoro-2-chloroethane and hydrogen fluoride gas phase fluorination synthesizes HFC-134a, controls 1,1,1-trifluoro-2-chloroethane and hydrofluoric charge ratio is 1:5(mol ratio), reaction temperature 330 DEG C.The conversion ratio of 1,1,1-trifluoro-2-chloroethane is shown in Fig. 2.

Claims (2)

1. a preparation method for fluorination catalyst, is characterized in that: comprise the following steps:

Step 1: activity component metal salt is preferably according to Co/Cr the atomic ratio that 0.05 ~ 0.25, Y/Cr is preferably 0.01 ~ 0.15 and is mixed with solution;

Step 2: react as precipitating reagent using ammoniacal liquor, pH value controls between 7 ~ 9, and continues to stir aging 9 ~ 11min, filters, and spends deionized water to neutral;

Step 3: dried at the temperature of 100 ~ 150 DEG C by filter cake, finally in inert gas environment, carries out roasting, prepares catalyst precursor at 150 ~ 350 DEG C of temperature;

Step 4: pulverized by catalyst precursor, and be mixed into the graphite of 2% ~ 4%, the pressed powder mixed to hand is pinched not broken, at the temperature of 200 ~ 400 DEG C, passes into inert gas and hydrofluoric gaseous mixture is fluoridized, prepares required catalyst.

2. the preparation method of a kind of fluorination catalyst according to claim 1, is characterized in that: the activity component metal salt in described step 1 is nitrate, villaumite or sulfate.