CN1273426C - Preparation of high purity, 1,1,1-trifluoro-2,2,-dichloroethane - Google Patents

Abstract

The present invention discloses a method for preparing high-purity 1, 1, 1-trifluoro-2, 2-dichloroethane, which belongs to the technical field of organic fluorine chemical engineering. Mixed gas which contains trifluoro-chloroethane, trifluoro-dichloroethane and trichloro-trifluoroethane is obtained by fluorination and thermal chlorination of trichloroethylene, the mixed gas passes through cocoanut active charcoal, the catalytic chlorination reaction of the mixed gas is carried out at the temperature of 160 DEG C to 250 DEG C, the gas after the reaction is washed by thermonatrite, fractionated and condensed to obtain pure trifluoro-dichloroethane. On the basis of the existing technological line, a catalytic chlorination reactor is directly added after a thermal chlorination section of an original technology, an original thermonatrite washing system is connected, the high-purity 1, 1, 1-trifluoro-2, 2-dichloroethane product can be obtained by the direct common fractionation in an original system and the technological operation is simple. Residual energy and chlorine gas of thermal chlorination reaction are used for the catalytic chlorination reaction, the energy utilization ratio is enhanced, the exhaust of residual chlorine gas in the process is reduced, loads of thermonatrite washing and condensation are reduced, and clean production is realized.

Description

A kind of preparation high purity 1,1, the method for 1-three fluoro-2,2 ethylene dichloride

Technical field

The invention belongs to the organic fluorine chemical technology field, being particularly related to the catalytic chlorination method purifies by the trieline mixed gas that contains trifluoro-chloroethane, trifluorobichloroethane, Freon 113 that is raw material through fluoridizing, obtaining after the thermal chlorination with preparation high purity 1,1,1-three fluoro-2,2 ethylene dichloride (R123) method for product

Background technology

1,1,1-three fluoro-2, the 2-ethylene dichloride is called for short trifluorobichloroethane, and trade name is HCFC-123 or R123, and the GWP of product and ODP value are 0.02.R123 has very wide Application Areas, and R123 is mainly used in and substitutes R11 as large-scale handpiece Water Chilling Units cooling agent in refrigeration working fluid; In fire protection sector, R123 mixes with other component, can be used as the substitute of breathing out dragon 1301; The alternative R113 of R123 is as clean-out system, whipping agent simultaneously; Also can be used as raw material and produce pentafluoride ethane (R125) and trifluoracetic acid etc., as raw materials for production, the purity requirement of R123 is high, generally all more than 99.8%.

Its crude product purity does not all reach requirement in the production process route of prior art.That adopts at present at first synthesizes trifluoro-chloroethane (R133a) for its beginning raw material through fluoridizing with trieline, and then makes the operational path of trifluorobichloroethane (R123) through thermal chlorination.Contain trifluoro-chloroethane, trifluorobichloroethane Freon 113 and other impurity in the mixed gas in this operational path after the thermal chlorination.Contained impurity is hexafluoro chlorobutylene (R1326) particularly, and it not only has big toxicity, and is also very big to the human and environment influence, is controlled substance in the R123 product.And R1326 can and be difficult to eliminate by the distillatory method with trifluorobichloroethane (R123) formation azeotrope.

In industry and scientific research, the method for preparing highly purified trifluorobichloroethane is mainly the purification by liquid extraction method, Japanese Patent " Te Kaiping-279274 ", the method that adopts sulfoxide, acid amides, carbonates extraction agent purification R123 is disclosed, it is less that but the selected extraction agent of this method increases relative volatility α value, and separating effect is relatively poor.

Chinese patent CN1270156A proposes improvement project, and alcohols, ester class, ketone, cyanogen class, alkane substitute class or its mixture of selection standard boiling point in 55-160 ℃ of scope is extraction agent.Remove the hexafluoro chlorobutylene by extracting rectifying, again by distilling the trifluorobichloroethane of purifying.But also existing problems, as ketone extraction agent (as pimelinketone) to the toxic effect of human body; Autohemagglutination easily takes place in the treating processes, forms black heavy-gravity polymer substance and stops up process pipeline; The extraction agent large usage quantity, cost strengthens.

Commonly used removing in the method for alkene as light chlorination process, the operational condition harshness, very inconvenience in the actually operatings such as light source selection, fader control, temperature requirement, and by product is many, increase fractionation burden; The shortening method, hydrogen precious metal/the C catalyst that uses costs an arm and a leg, and cost is too high, the catalyzer that this class catalyzer of while also is a dechlorination reaction, chlorine that produces in the reaction process or hydrogenchloride heavy corrosion conversion unit, and can produce other olefin impurity.

U.S. Pat 6,414,203 disclose the treatment process that adopts the olefin impurity in the activated carbon catalysis chlorination method removal R245fa product.Main physical property is good because the gac source is wide, and processing is simple, and acid resistance is good.It is undesirable that but common activated-carbon catalyst is removed the olefin impurity effect, and poor selectivity, do not have alternative activated carbon catalysis chlorination method purification trifluorobichloroethane product in prior art trifluorobichloroethane purifying technique.

Summary of the invention

The objective of the invention is to select a kind of higher activated-carbon catalyst that removes the alkene effect and select effect that has, the mixed gas after the catalytic chlorination thermal chlorination is with preparation high purity 1,1, the preparation method of 1-three fluoro-, 2,2 ethylene dichloride (R123) product,

Second purpose of the present invention is to utilize thermal chlorination reaction energy remaining and chlorine, improves the discharging of capacity usage ratio and minimizing process residue chlorine, and technological operation is simple, the production environmental protection.

The 3rd purpose of the present invention is to utilize material temperature and residue chlorine by catalytic chlorination, reduced that scale is washed and the load of condensation process.

Above-mentioned purpose of the present invention is achieved through the following technical solutions:

A kind of preparation high purity 1,1,1, the method of-three fluoro-2,2 ethylene dichloride, trieline is through fluoridizing, obtain containing after the thermal chlorination mixed gas of trifluoro-chloroethane, trifluorobichloroethane, Freon 113, it is characterized in that through the coconut husk activated carbon, catalytic chlorination reacts under 160 ℃～250 ℃ temperature with mixed gas, reaction back gas is washed through scale, condensate fractionation gets 1,1, and 1,-three fluoro-2,2 ethylene dichloride.

The gac that described catalytic chlorination reaction is used is particulate state coconut husk activated carbon, and gac soaks through hydrofluoric acid solution, and again through washing and drying, the back is by the chlorine activation, and the particle diameter of gac is 2～4 millimeters.

It is corrosion-resistant withstand voltage materials such as nickel pipe, stainless steel tube or ceramic reactor that described catalytic chlorination is reflected at the material that can select reactor in the industrial actual production for use.Temperature of reaction can be controlled at 160-300 ℃, and catalytic chlorination reaction response temperature can not be too high, otherwise causes the product loss as the R123 chlorination of product.When temperature of reaction reached more than 250 ℃, the thermal chlorination reaction effect was better, and olefin impurity is removed basically, but product R123 loss is relatively large; When temperature of reaction is lower than 160 ℃, it is bad to remove the alkene effect.Therefore temperature of reaction is controlled to be between 180-220 ℃.

Weight ratio by flow rate control chlorine/mixed gas in the catalytic chlorination reaction is preferably 1: 10～and 100; Chlorine/mixed gas weight ratio the best is 0.1, and temperature of reaction the best is 220 ℃.

The present invention adopts the particulate state coconut husk activated carbon that soaks through the hydrofluoric acid solution of concentration more than 30%, in hydrofluoric acid solution, soak in the coconut husk activated carbon, its carbonyl group is destroyed, and has eliminated the possibility that forms other byproducts or impurity in the activated carbon catalysis chlorination reaction process.Gac after the immersion cleans with distilled water, through carrying out drying to the high temperature more than 120 ℃, fully removes moisture again, improves the purity of gac, guarantees stability in the catalytic chlorination process and to effective removal of olefin impurity; Dried gac can carry out activation treatment with nitrogen earlier under temperature of reaction, further remove the moisture or the ashes that may exist, activate with chlorine then, purpose is that chlorine is fully adsorbed on the surface of activated-carbon catalyst, can carry out gas-phase reaction with the thermal chlorination gas mixture.

The present invention is based on the existing processes route, thermal chlorination section back in original technology directly adds a catalytic chlorination reactor, inserts original scale and washes and enter original system and directly carry out common fractionation and can obtain high purity 1,1,1-three fluoro-2,2 ethylene dichloride products.The filling of coconut husk activated carbon, scale are washed and condensation collection product is a catalytic chlorination technology ordinary method.With the coconut husk activated carbon is gas mixture after catalyzer carries out the catalytic chlorination thermal chlorination, what contain in the mixed gas can reduce until removing greatly with the impurity that R123 forms azeotrope, make difficult fractionated olefin impurity change into easy fractionated component, through scale wash with common fractionation after get final product.Through behind the existing three wastes treatment process, just can obtain the very high R123 product of purity through fractionation again.Show that through experiment the mixed gas after the thermal chlorination is all remaining on more than 99.8% through the R123 product content that obtains after the fractionation, R1326 alkene all below 10ppm in addition content be zero.

The present invention adopts in the direct feeding catalysis thermal chlorination device of the mixed gas that obtains after the thermal chlorination, so not only simplifies technical process, and effectively utilizes heat and residue chlorine in the gas stream, improves the energy and chlorine utilising efficiency, has saved cost.Simultaneously, the regeneration of coconut husk activated carbon is comparatively convenient, adopts hydrogen, air or oxygen incendiary method to get final product, even the gac inactivation can be used as fuel treatment, and can any pollution of environment.

The beneficial effect for preparing the method for high purity trifluorobichloroethane of the present invention mainly shows:

1, utilized the utilization ratio of chlorine excessive in thermal chlorination reaction back energy remaining, the raising thermal chlorination technology, save energy has reduced production cost;

2, the minimizing of reduction of material temperature degree and amount of chlorine, scale is washed and the load of condensation process reduces.

3, save extraction process in original technology, production process method environment protection clean.

4, the present invention earlier carries out the gas mixture after the thermal chlorination catalytic chlorination and handles, and makes difficult fractionated olefin impurity change into easy fractionated component and directly carries out common fractionation and just can obtain the R123 product of purity more than 99.8%.

Embodiment

Below in conjunction with embodiment the present invention is further described.

Embodiment 1

Fluoridize chlorination: by trieline through fluoridizing synthetic trifluoro-chloroethane (R133a), obtain containing the mixed gas of trifluoro-chloroethane (R133a), trifluorobichloroethane (R123), Freon 113 (R113a) and other impurity after the thermal chlorination, through deacidification, olefin impurity 〉=2000ppm.

The coconut husk activated carbon is prepared: select the granular coconut husk activated carbon of average diameter of particles at the 2-4 millimeter for use, the hydrofluoric acid solution with concentration 30% fully soaks earlier.Clean with distilled water then, the gac after the cleaning send in the baking oven at least under 120 ℃ or higher temperature and carries out drying, fully to remove moisture; Can under temperature of reaction, carry out activation treatment with nitrogen earlier, further remove the moisture or the ashes that may exist, and then activate for some time, reach chlorine fully absorption on the surface of activated-carbon catalyst with chlorine,

Catalytic chlorination: the chlorine gaseous feed, adopt control device to control the inlet amount of the mixed gas of chlorine and thermal chlorination reaction, weight ratio is 2: 20, enters tubular reactor through threeway.The treated coconut husk activated carbon catalyzer of filling utilizes the temperature controller control reaction temperature to be 160 ℃ and reacts in the reaction tubes.Reacted gas is washed through scale, removes the acidic substance that produce in the dereaction, collects product through condenser condenses then, and condensed product is sampled to chromatographic instrument analysis.

Coconut husk activated carbon filling, scale are washed, condensation collection product and other are catalytic chlorination technology ordinary method, do not do tired stating at this.

Repeat the aforesaid operations step, control reaction temperature is carried out the catalytic chlorination reaction under 180 ℃, 200 ℃, 220 ℃ and 250 ℃, and the product that each time condensation is collected is got liquid phase analyze to chromatographic instrument.

Each time test-results sees Table 1.

Table 1

Component	Temperature (℃)
						160	180	200	220	250
	R1326(ppm) R123(％) R133a(％) R113a(％)	385 56.336 36.39 6.505	40 51.884 39.997 7.396	0 44.005 44.042 11.212	0 37.22 44.849 16.826						0 26.967 27.13 41.199

Embodiment 2

The temperature of reaction of catalytic chlorination keep 200 ℃ constant, the mixed gas that chlorine and thermal chlorination obtain controlled inlet amount at 1/40,1/20,1/10 o'clock respectively with weight ratio, all the other are with embodiment 1.

The test-results of each time sees Table 2.

Table 2

Component	Feed weight is than (g/g)
				0.025	0.5	0.1
	R1326(ppm) R123(％) R133a(％) R113a(％)	63617.5 68.973 2.364 26.483	0 66.529 4.49 26.955				59.702 8.218 30.567

Embodiment 3

Contained R113a, R133a, the amount of R123, R1326 see Table 3 in the mixed gas that thermal chlorination obtains.

When the temperature of reaction of catalytic chlorination reaction was 200 ℃, the weight ratio of the mixed gas charging that control chlorine and thermal chlorination obtain was respectively 2/30,2/20,1/10,1/20, and all the other are with embodiment 1.

When the temperature of reaction of catalytic chlorination reaction was 180 ℃, control chlorine was respectively 1/10 with the feed weight ratio of mixed gas, and all the other are with embodiment 1.

The liquid-phase chromatographic analysis that each secondary response product is mainly formed the results are shown in Table 3.

Table 3

T ℃	M g/g	Reaction product is mainly formed				Remarks
							area％			ppm
		R113a	R133a	R123	R1326
							Mixed gas		9.714	28.092	60.409	0.2274	√
200	2/30	6.876	51.933	40.670	0.0040
								1/10	12.977	19.310	36.737	0/0
	1/20	9.499	45.903	43.980	0.0032
							180	1/10	13.282	49.343	35.028	0/0

Remarks column is beaten the analytical results for R113a, R133a, R123, R1326 in the mixed gas that obtains after the thermal chlorination that colludes in the table.

Embodiment 4

R113a, R133a, R123, R1326 content see Table 4 in the mixed gas after the thermal chlorination, in the catalytic chlorination reaction, the weight ratio of the charging of chlorine and thermal chlorination gained mixed gas is 2/10, and each secondary response temperature and condensation collection product analytical results see Table 4, and all the other are operated with embodiment 1.

Table 4

No.	T ℃	M g/g	Reaction product is formed area%/ppm				Remarks
								R113a	R133a	R123	R1326
			Mixed gas			11.393						21.459	65.164	0.2612/3992	√
1	200	2/20					19.312	39.068	41.139	0/0
			2	180	2/20	9.934						38.991	49.976	0/0
3	170	2/20					9.803	34.168	55.295	0/0
			4	160	2/20	9.001						33.262	58.033	0.0030/52

Remarks column is beaten the analytical results for R113a, R133a, R123, R1326 in the mixed gas that obtains after the thermal chlorination that colludes in the table

The experiment of embodiment 5 catalyst stabilities

R113a, R133a, R123, R1326 content are shown in Table 5 in the mixed gas after twice thermal chlorination, and each time mixed gas feeds the catalytic chlorination reactor and carries out the catalytic chlorination reaction.

The mixed gas feed weight that the temperature of reaction of catalytic chlorination reaction, chlorine and thermal chlorination obtain sees Table 5 than the mixed gas after, the thermal chlorination and the weight ratio of coconut husk activated carbon catalyzer.

Reactions steps is with embodiment 1.

Table 5

N o .	T ℃	M g/g	Gas mixture input speed w/w.h	Gas mixture/catalyzer g/g	Reaction product is formed area%/ppm				The raw material remarks
										R113a	R133a	R123	R1326
															22.878	3.149	69.180	0.2744/3956	√
1	200	2/20	1.5	3.2					21.062	29.178	48.867	0/0
					2	180	2/20	1.52						18.2	16.423	14.435	68.222	0/0
3	160	2/20	1.52	31.6					15.342	7.585	75.864	0.0074/98
					4	180	2/20	1.56						78.8	5.758	42.011	47.179	0/0
5	160	2/20	1.54	94.9					8.508	32.962	57.722	0/0
					6	160	2/20	1.54						117.4	8.565	27.945	62.798	0.0021/3
									23.629	2.741	69.936	0.1187/1719	√
					7	160	2/20	1.54						160	15.186	7.341	75.929	0.0042/55
8	160	2/30	1.54	213.6					5.17	47.852	44.907	0.0061/136
					9	200	2/30	1.62						248.2	14.711	33.483	50.804	0.0005/10

	200	2/40	1.66	262.2	12.791	31.818	54.504	0/0
											200	2/100	1.92	334	15.883	13.871	68.595	0.364/530

Remarks column is beaten the analytical results for R113a, R133a, R123, R1326 in the mixed gas that obtains after the thermal chlorination that colludes in the table

Embodiment 6 regeneration tests

Get the gac of reaction back inactivation among the embodiment 5, soaked 12 hours with 35% hydrofluoric acid solution earlier, wash with water to neutrality or slightly acidic again, the nitrogen that places the reactor feeding to contain 1%O2 was handled 24 hours at 250 ℃.

Mixed gas that obtains after the thermal chlorination with R113a shown in the table 6, R133a, R123, R1326 content and chlorine feed reactor, carry out the catalytic chlorination reaction, temperature of reaction and chlorine see Table 6 with gas mixture feed weight ratio, and the concrete operations step is with embodiment 1.

Table 6

No.	T ℃	M g/g	Reaction product is formed area%/ppm				Remarks
								R113a	R133a	R123	R1326
			Mixed gas			23.210						4.575	67.52	0.1817/2684	√
1	180	2/10					18.977	10.84	69.183	0.0009/13
			2		2/10	19.387						10.422	69.194	0.0008/12
3	200	2/10					30.432	8.309	59.689	0/0
			4		2/10	30.703						8.127	59.715	0/0
5	200	2/20					26.789	4.593	66.593	0.0011/17
			6		2/20	27.12						4.387	66.465	0.0012/18
7	200	2/40					26.483	2.372	68.948	0.0438/635
			8		2/40	26.483						2.357	68.999	0.044/637

Remarks column is beaten the analytical results for R113a, R133a, R123, R1326 in the mixed gas that obtains after the thermal chlorination that colludes in the table

Embodiment 7

Press the inlet amount of table 7 control chlorine and thermal chlorination mixed gas, enter reactor through threeway, the cocoanut active charcoal catalyzer that filling is handled through 36% hydrofluoric acid dips in the reaction tubes, temperature of reaction is 218 ℃～242 ℃ and reacts, reacted gas is washed through scale, collect product through condenser condenses then, condensed product is got liquid phase and is analyzed to chromatographic instrument.

R113a, R133a before and after the gas mixture of each time test and the air input of chlorine, temperature of reaction and the processing, the content of R123 see Table 7.

Table 7

Reaction mixture gas m 3/h	Chlorine m 3/h	Temperature of reaction ℃	Lab scale product analysis %,
										R1326	R113a		R133a		R123
			Before the processing	After the processing	Before the processing	After the processing	Before the processing	After the processing
									60		1.5	218	0.0002	9.25	8.81	61.66	59.03	28.87	31.73
60	1.0	218	0.0004	8.58	7.47	61.31	62.0	29.86		30.22
									60		1.6	225	0.0003	10.153	6.68	62.011	65.76	27.67	27.58
60	1.4	243	0.0004	10.34	9.46	61.45	57.27	28.04		32.77
									60		1.5	279	0.0016	11.29	8.6	63.26	59.01	24.69	31.39
60	2.0	315	0.0047	15.29	8.72	55.75	59.36	28.30		30.96

Claims (2)

1, a kind of preparation high purity 1,1,1-three fluoro-2, the method of 2 ethylene dichloride, trieline is through fluoridizing, obtain containing after the thermal chlorination mixed gas of trifluoro-chloroethane, trifluorobichloroethane, Freon 113, it is characterized in that with mixed gas through the coconut husk activated carbon catalytic chlorination reaction under 160 ℃～250 ℃ temperature, reaction back gas is washed through scale, condensate fractionation gets 1,1,1-three fluoro-2,2 ethylene dichloride, the coconut husk activated carbon that described coconut husk activated carbon is crossed for the hydrofluoric acid solution immersion treatment.

2, preparation high purity 1 as claimed in claim 1,1, the method for 1-three fluoro-2,2 ethylene dichloride, it is characterized in that the weight ratio by flow rate control chlorine/mixed gas is 1: 10～100 in the catalytic chlorination reaction, the preferable controlling valu of temperature of reaction is 180 ℃～220 ℃.