Method for Preparing Methyl Formate and Coproducing Dimethyl Ether

Abstract

Method for preparing methyl formate and coproducing dimethyl ether by reacting a formaldehyde and methanol raw material (molar ratio range of 1:4 to 1:0.05) in a First Reaction Region at ranges from 50° C. to 100° C. with Catalyst A resulting in post-reaction material separated into Constituent I. Reacting Constituent I in a Second Reaction Region at ranges from 50° C. to 200° C. and from 0.1 MPa to 10 MPa with Catalyst B resulting in post-reaction material, which is separated into methyl formate, dimethyl ether and Constituent II. At least 1% of dimethyl ether is product, and recycling the rest to the First Reaction Region. Constituent II is recycled to the Second Reaction Region. Each component is gaseous phase and/or liquid phase, independently. The method shows long catalyst life, mild reaction condition, high utilization ratio of raw materials, continuous production and large scale industrial application potential.

Claims

1. A method for preparing methyl formate and coproducing dimethyl ether, which at least contains the steps as follows: a) introducing a raw material containing formaldehyde and methanol into a First Reaction Region and contacting with a Catalyst A to react, and separating the post-reaction material to obtain Constituent I; b) introducing the Constituent I obtained in step a) into a Second Reaction Region and contacting with a Catalyst B to react, and separating the post-reaction material to obtain Constituent II, dimethyl ether and the product methyl formate; c) taking at least 1% of dimethyl ether obtained in step b) as product, and recycling the rest of dimethyl ether obtained in step b) to the First Reaction Region and recycling the Constituent II to the Second Reaction Region; wherein in step a), the reaction temperature of the First Reaction Region ranges from 50° C. to 100° C.; in said raw material, the molar ratio range of formaldehyde to methanol is from 1:4 to 1:0.05, and the molar of formaldehyde and methanol are calculated according to the molar of carbon atoms contained in formaldehyde and methanol, respectively; the weight hourly space velocity of formaldehyde in the raw material ranges from 0.01 h.sup.−1 to 15.0 h.sup.−1; wherein in step b), the reaction temperature of the Second Reaction Region ranges from 50° C. to 200° C. and the reaction pressure ranges from 0.1 MPa to 10 MPa; wherein each component in the First Reaction Region and the Second Reaction Region is gaseous phase and/or liquid phase, independently.

2. A method for preparing methyl formate and coproducing dimethyl ether according to claim 1, wherein in step a), the Catalyst A is loaded in a distillation reaction device; and in the distillation reaction device, the reflux ratio ranges from 0.5 to 10, and the temperature ranges from 60° C. to 90° C.; the weight hourly space velocity of formaldehyde in the raw material ranges from 0.5 h.sup.−1 to 3.0 h.sup.−1.

3. A method for preparing methyl formate and coproducing dimethyl ether according to claim 1, wherein in step c), at least 10% of dimethyl ether obtained in step b) is taken as product, and recycling the rest of dimethyl ether obtained in step b) to the First Reaction Region.

4. A method for preparing methyl formate and coproducing dimethyl ether according to claim 1, wherein in step c), at least 90% of dimethyl ether obtained in step b) is taken as product, and recycling the rest of dimethyl ether obtained in step b) to the First Reaction Region.

5. A method for preparing methyl formate and coproducing dimethyl ether according to claim 1, wherein in step a), the Catalyst A is a strong acidic cation exchanger resin.

6. A method for preparing methyl formate and coproducing dimethyl ether according to claim 1, wherein in step a), the Catalyst A is a sulfonated styrene-divinylbenzene copolymer resin with strong acid and macro-pores.

7. A method for preparing methyl formate and coproducing dimethyl ether according to claim 1, wherein in step b), the reaction temperature of the Second Reaction Region ranges from 60° C. to 150° C. and the reaction pressure ranges from 0.1 MPa to 2 MPa.

8. A method for preparing methyl formate and coproducing dimethyl ether according to claim 1, wherein in step b), the Catalyst B is at least one selected from acid molecular sieves or strong acidic cation exchanger resins.

9. A method for preparing methyl formate and coproducing dimethyl ether according to claim 1, wherein in step b), the Catalyst B is at least one selected from H-type MCM-22 zeolite, H-type ZSM-5 zeolite, H-type Y zeolite, H-type BETA zeolite, H-type ferrierite, H-type mordenite or perfluorosulfonate resin.

10. A method for preparing methyl formate and coproducing dimethyl ether according to claim 1, wherein the Second Reaction Region is composed of a fixed-bed reactor; or the Second Reaction Region is composed of a number of fixed-bed reactors in parallel and/or in series.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 is a technological flow sheet of an embodiment of the present application.

[0032] FIG. 2 is a technological flow sheet of an embodiment of the present application.

[0033] FIG. 3 is the technological flow sheet for preparing methyl formate and coproducing dimethyl ether in Example 1.

[0034] FIG. 4 is the technological flow sheet for preparing methyl formate and coproducing dimethyl ether in Example 2.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] As an embodiment of the present application, the technological flow sheet is shown in FIG. 1. The raw material containing formaldehyde and methanol is introduced into a First Reaction Region, and after reacting and separating, the unreacted raw materials continue reacting in the First Reaction Region; and the Constituent I (mainly methylal), which is obtained by separating the post-reaction material of the First Reaction Region, is introduced into a Second Reaction Region; and the post-reaction material of the Second Reaction Region is separated to obtain dimethyl ether, methyl formate and Constituent II (mainly methylal); and dimethyl ether and methyl formate are stored as the products, respectively; and the Constituent II (mainly methylal) is recycled to the Second Reaction Region.

[0036] As other embodiment of the present application, the technological flow sheet is shown in FIG. 2. The raw material containing formaldehyde and methanol is introduced into a First Reaction Region, and after reacting and separating, the unreacted raw materials continue reacting in the First Reaction Region; and the Constituent I (mainly methylal), which is obtained by separating the post-reaction material of the First Reaction Region, is introduced into a Second Reaction Region; and the post-reaction material of the Second Reaction Region is separated to obtain dimethyl ether, methyl formate and Constituent II (mainly methylal); and part of dimethyl ether is stored as the product and the rest of dimethyl ether is recycled to the First Reaction Region; and methyl formate is stored as the product; and the Constituent II (mainly methylal) is recycled to the Second Reaction Region.

[0037] The present application will be further described by combining with Examples. It should be understand that these Examples are only used to illustrate the present application and not to limit the scope of the present application.

[0038] Without special explanation, the reagents and catalysts in the Examples are from commercial purchase. Amberlyst-15 Resin is a sulfonated styrene-divinylbenzene copolymer resin with strong acid and macro-pores, purchased from ROHM HRRS Company.

[0039] DNW Resin and D005 Resin are sulfonated styrene-divinylbenzene copolymer resin with strong acid and macro-pores, purchased from Dandong Mingzhu Special Resin Limited Company.

[0040] D006 Resin and D007 Resin are sulfonated styrene-divinylbenzene copolymer resin with strong acid and macro-pores, purchased from Cary environmental technology co., LTD.

[0041] In the Examples, analysis method and calculation method of percent conversion and selectivity are as follows:

[0042] The components of gas/liquid phase are auto analyzed using Agilent7890 gas chromatograph with gas autosampler, FID detector and PLOT-Q capillary column.

[0043] In the Examples of the present application, the calculation of percent conversion per pass of methylal and selectivity per pass of methyl formate and dimethyl ether are based on the carbon mole number.

Percent conversion per pass of methylal=[(the carbon mole number of methylal in the feedstock of Second Reaction Region)−(the carbon mole number of methylal in the discharge of Second Reaction Region)]÷(the carbon mole number of methylal in the feedstock of Second Reaction Region)×(100%)

Selectivity per pass of methyl formate=(the carbon mole number of methyl formate in the discharge of Second Reaction Region)÷[(the carbon mole number of methylal in the feedstock of Second Reaction Region)−(the carbon mole number of methylal in the discharge of Second Reaction Region)]×(100%)

Selectivity per pass of dimethyl ether=(the carbon mole number of dimethyl ether obtained by the conversion of methylal in the discharge of Second Reaction Region)÷[(the carbon mole number of methylal in the feedstock of Second Reaction Region)−(the carbon mole number of methylal in the discharge of Second Reaction Region)]×(100%)

Proportion of the product dimethyl ether=[(the carbon mole number of dimethyl ether obtained by the conversion of methylal in the Second Reaction Region)−(the carbon mole number of dimethyl ether recycled to the First Reaction Region)]÷(the carbon mole number of dimethyl ether obtained by the conversion of methylal in the Second Reaction Region)×(100%)

[0044] In the present application, the carbon mole number is the mole number of carbon atoms in each component.

[0045] The present application will be described in details by Examples, but the present application is not limited to these Examples.

Example 1

[0046] The technological process for preparing methyl formate and coproducing dimethyl ether:

[0047] As a typical embodiment of the present application, the technological flow sheet for preparing methyl formate and coproducing dimethyl ether was shown in FIG. 3. A catalytic distillation tower was used in the First Reaction Region to carry out the condensation reaction of formaldehyde and methanol for preparing methylal; and a fixed-bed reactor was used in the Second Reaction Region to carry out the disproportionated reaction of methylal; and a First Separating Unit was used to separate dimethyl ether from the products of disproportionated reaction of methylal; and a Second Separating Unit was used to separate methyl formate and the unreacted raw materials from the products of disproportionated reaction of methylal.

[0048] Specifically, the raw material contained formaldehyde aqueous solution and methanol; the raw material was introduced into the catalytic distillation tower of the First Reaction Region; and after the raw material contacts with the catalyst bed, the constituent containing formaldehyde, methanol and dimethyl ether was returned to the catalyst bed in the catalytic distillation tower to continue reacting, and the Constituent I mainly was methylal of the condensation reaction product which was obtained from tower top, and water of the condensation reaction product was obtained from tower bottom. The Constituent I was introduced into the Second Reaction Region for disproportionated reaction of methylal. The Flow III of disproportionated reaction product was introduced into the First Separating Unit to obtain the product dimethyl ether and Flow IV by separating; and the Flow IV was introduced into the Second Separating Unit to obtain the product methyl formate and Constituent II by separating; and the Constituent II mainly was methylal used to be recycled; and the Constituent II was recycled to the Second Reaction Region to continue reacting. Using the above-mentioned process, the product, in which the carbon molar number ratio of methyl formate to dimethyl ether was approximate 1:2, was obtained using formaldehyde and methanol as raw materials.

[0049] In the First Reaction Region, the process of the condensation reaction of formaldehyde and methanol for preparing methylal was according to the following steps:

[0050] In a stainless steel catalytic distillation tower with an internal diameter of 30 mm and a height of 1800 mm, 500 g of Amberlyst-15 Resin catalyst packed by stainless steel cloth was loaded at lower end of the tower as the reaction zone with a height of 1200 mm; and the Φ4 mm×4 mm of stainless steel wire was loaded at upper end of the tower as the packing of rectification zone with a height of 600 mm. The reflux ratio of the tower top condenser could be controlled. The volume of the tower bottom reboiler was 3000 ml. The heater wires were winded around the outer wall of reaction zone to make temperature from top down equably increase from 60° C. to 90° C. 37% of formaldehyde aqueous solution, 96% of methanol aqueous solution and dimethyl ether from the Second Reaction Region in sequence were introduced into three feed inlets of the catalytic distillation tower from top down. The ratio of formaldehyde to methanol was listed in Table 1. The proportion of the product dimethyl ether to the total dimethyl ether in the discharge of Second Reaction Region was listed in Table 1, and the rest of dimethyl ether was recycled to the catalytic distillation tower of the First Reaction Region. Gradually adjusting the power of reboiler and the reflux ratio, until more than 99.5% of methylal was obtained from the tower top.

[0051] In the Second Reaction Region, the process of the disproportionated reaction of methylal for preparing methyl formate and coproducing dimethyl ether is according to the following steps:

[0052] 300 g of H-type MCM-22 with the atom ratio of Si/Al=40:1 was calcinated in air at 550° C. for 5 hours in Muffle furnace, and then part of the powder sample was taken, pressed, crushed and sieved to 20-40 mesh sample used for the catalytic performance testing. 200 g of the above-mentioned H-type MCM-22 sample was weighed and loaded into a stainless steel reaction tube with an internal diameter of 30 mm. The sample was activated at 550° C. for 4 hour under nitrogen gas at atmospheric pressure and the temperature was reduced to 90° C., and then the methylal obtained from the First Reaction Region was introduced and the pressure was 0.1 MPa. The reaction products were analyzed by a gas chromatograph. After the reaction being stable, the percent conversion per pass of methylal and the selectivity per pass of methyl formate were calculated. The results were shown in Table 1. The products of the Second Reaction Region were separated by two-stage rectified to obtain methyl formate, dimethyl ether and the unreacted methylal; wherein methyl formate and dimethyl ether were stored as the products respectively and the unreacted methylal was recycled to the Second Reaction Region.

[0053] Combining the two reactions, it was achieved that more than 99.99% of methyl formate and dimethyl ether was obtained using 37% of formaldehyde aqueous solution and 96% of methanol aqueous solution as the raw materials.

Example 2

[0054] The technological process for preparing methyl formate and coproducing dimethyl ether:

[0055] As a typical embodiment of the present application, the technological flow sheet for preparing methyl formate and coproducing dimethyl ether was shown in FIG. 4. A catalytic distillation tower was used in the First Reaction Region to carry out the condensation reaction of formaldehyde, methanol and dimethyl ether for preparing methylal; and a fixed-bed reactor was used in the Second Reaction Region to carry out the disproportionated reaction of methylal; and a First Separating Unit was used to separate dimethyl ether from the products of disproportionated reaction of methylal; and a Second Separating Unit was used to separate methyl formate and the unreacted raw materials from the products of disproportionated reaction of methylal.

[0056] Specifically, the raw material contained fresh formaldehyde aqueous solution, fresh methanol and recycling dimethyl ether; the raw material was introduced into the catalytic distillation tower of the First Reaction Region; and after the raw material contacts with the catalyst bed, the constituent containing formaldehyde, methanol and dimethyl ether was returned to the catalyst bed in the catalytic distillation tower to continue reacting, and the Constituent I mainly was methylal of the condensation reaction product which was obtained from tower top, and water of the condensation reaction product was obtained from tower bottom. The Constituent I was introduced into the Second Reaction Region for disproportionated reaction of methylal. The Flow III of disproportionated reaction product was introduced into the First Separating Unit to obtain dimethyl ether and Flow IV by separating; and part of dimethyl ether was as the product and the rest of dimethyl ether was recycled to the First Reaction Region. The Flow IV was introduced into the Second Separating Unit to obtain the product methyl formate and Constituent II by separating; and the Constituent II mainly was methylal used to be recycled; and the Constituent II was recycled to the Second Reaction Region to continue reacting. Using the above-mentioned process, it was realized that the product of methyl formate and dimethyl ether was prepared using formaldehyde and methanol as raw materials. And the ratio of methyl formate to dimethyl ether in the product could be controlled by adjusting the ration of the product dimethyl ether to the recycling dimethyl ether. The proportion of the recycling dimethyl ether to the total dimethyl ether obtained in the Second Reaction Region was higher, and the proportion of the product dimethyl ether was lower, the proportion of methyl formate in the product was higher.

[0057] The Catalyst A in the First Reaction Region, the Catalyst B in the Second Reaction Region, the proportion of the product dimethyl ether to the total dimethyl ether obtained in the Second Reaction Region, the raw material ratio, the weight hourly space velocity (WHSV) of formaldehyde in the raw material, the reaction temperature in the Second Reaction Region, the reaction pressure in the Second Reaction Region were shown in Table 1. The rest experimental procedure was same as Example 1. The results were shown in Table 1.

Example 3

[0058] The Catalyst A in the First Reaction Region, the Catalyst B in the Second Reaction Region, the proportion of the product dimethyl ether to the total dimethyl ether obtained in the Second Reaction Region, the raw material ratio, the weight hourly space velocity (WHSV) of formaldehyde in the raw material, the reaction temperature in the Second Reaction Region, the reaction pressure in the Second Reaction Region were shown in Table 1. The rest experimental procedure was same as Example 1. The results were shown in Table 1.

Examples 4 to 6

[0059] The Catalyst A in the First Reaction Region, the Catalyst B in the Second Reaction Region, the proportion of the product dimethyl ether to the total dimethyl ether obtained in the Second Reaction Region, the raw material ratio, the weight hourly space velocity (WHSV) of formaldehyde in the raw material, the reaction temperature in the Second Reaction Region, the reaction pressure in the Second Reaction Region were shown in Table 1. The rest experimental procedure was same as Example 2. The results were shown in Table 1.

Examples 7 and 8

[0060] The Catalyst B in the Second Reaction Region was shown in Table 1. 200 g of the 20-40 mesh samples were weighed and loaded into a stainless steel reaction tube with an internal diameter of 30 mm. Before reacting, the samples were activated at 100° C. for 1 hour under nitrogen gas at atmospheric pressure. The Catalyst A in the First Reaction Region, the proportion of the product dimethyl ether to the total dimethyl ether obtained in the Second Reaction Region, the raw material ratio, the weight hourly space velocity (WHSV) of formaldehyde in the raw material in the First Reaction Region, the reaction temperature in the Second Reaction Region, the reaction pressure in the Second Reaction Region were shown in Table 1. The rest experimental procedure was same as Example 1. The results were shown in Table 1.

Example 9

[0061] The Second Reaction Region was composed of two fixed-bed reactors in series. Each fixed-bed reactor was loaded by 100 g of the Catalyst B. Other reaction conditions were shown in Table 1. The rest experimental procedure was same as Example 7. The results were shown in Table 1.

Example 10

[0062] The Second Reaction Region was composed of two fixed-bed reactors in parallel. Each fixed-bed reactor was loaded by 100 g of the Catalyst B. Other reaction conditions were shown in Table 1. The rest experimental procedure was same as Example 7. The results were shown in Table 1.

TABLE-US-00001 TABLE 1 Reaction conditions and results in Examples 1 to 10 WHSV of CH.sub.2O Catalyst Molar ratio of in raw Reaction Reaction Selectivity life per carbons in raw material temperature pressure Percent per Selectivity Proportion pass in Catalyst A Catalyst B material of the of the First in the in the conversion pass of per of the the in the in the First Reaction Reaction Second Second per pass of methyl pass of product Second First Second Region Region Reaction Reaction methylal formate dimethyl dimethyl Reaction Example Reaction Reaction (CH.sub.2O:CH.sub.3OH) (h.sup.−1) (° C.) (MPa) (%) (%) ether (%) ether (%) (day) 1 Amberlyst- H-type 1:2   3.0 90 0.1 78.4 33.2 66.3 100 150 15 Resin MCM-22 (Si/Al = 40) 2 Amberlyst- H-type 1:1.8  0.5 150 2 94.2 33.2 66.2 90 160 15 Resin ferrierite (Si/Al = 10) 3 DNW H-type 1:4   0.01 60 1 41.8 33.0 66.4 100 330 Resin ZSM-5 (Si/Al = 150) 4 D005 H-type 1:0.05 15 200 10 68.2 33.1 66.5 1 110 Resin mordenite (Si/Al = 3/1) 5 D006 H-type Y 1:0.2  6 50 5 39.2 33.1 66.4 10 150 Resin (Si/Al = 20) 6 D007 H-type 1:1   1.5 120 0.5 77.1 33.0 66.5 50 190 resin BETA (Si/Al = 15) 7 Amberlyst- Nafion-H 1:2   1.0 100 0.3 73.5 33.2 66.4 100 210 15 Resin Resin 8 Amberlyst- Amberlyst- 1:2   1.0 100 0.3 38.8 33.0 66.4 100 220 15 Resin 15 Resin 9 Amberlyst- Nafion-H 1:2   1.0 100 0.3 74.3 33.2 66.3 100 205 15 Resin Resin 1 Amberlyst- Nafion-H 1:2   1.0 100 0.3 73.5 33.0 66.4 100 220 0 15 Resin Resin Annotation 1: in Table 1, Amberlyst-15 Resin was purchased from ROHM HRRS Company. DNW Resin and D005 Resin were purchased from Dandong Mingzhu Special Resin Limited Company. D006 Resin and D007 Resin were purchased from Cary environmental technology co., LTD. Nafion-H was purchased from DuPont Company (USA). Annotation 2: the condition parameters in Table 1 were steady-state data.

[0063] The foregoing is detailed description of the present application for the sake of enabling those skilled in the art to understand the present application, however, it can be conceived that other variations and modifications can be made without departing from the scope covered by the claims of the present application, and all of these variations and modifications fall into the scope of protection of the present application.