STABILIZED PRODUCTION OF 1,3-BUTADIENE IN THE PRESENCE OF A TANTALUM OXIDE DOPED BY AN ALDOLIZING ELEMENT

Abstract

The invention relates to a catalyst that comprises at least the tantalum element, at least an aldolizing element and at least a mesoporous oxide matrix, with the tantalum mass being between 0.1 and 30% of the mesoporous oxide matrix mass, the mass of the at least one aldolizing element being between 0.02 and 4% of the mesoporous oxide matrix mass, and use thereof.

Claims

1. Catalyst that comprises at least the tantalum element, at least an aldolizing element that is selected from the group that consists of magnesium, calcium, barium, cerium and tin and mixtures thereof, and at least one mesoporous oxide matrix that comprises at least one oxide of an element X that is selected from among silicon, titanium and mixtures thereof, with the tantalum element mass being between 0.1 and 30% of the mesoporous oxide matrix mass, and the aldolizing element mass being between 0.02 and 4% of the mesoporous oxide matrix mass.

2. Catalyst according to claim 1, in which said aldolizing element is selected from the group that consists of calcium and barium and mixtures thereof.

3. Catalyst according to claim 1, also comprising at least one element that is selected from the group that consists of the elements of groups 1, 4 and 5 of the periodic table, with the mass of said element representing between 0.01 and 5% of the mesoporous oxide matrix mass.

4. Catalyst according to claim 3, also comprising at least one element that is selected from the group that consists of the element Cs and the element Nb and mixtures thereof, with the mass of said element representing between 0.01 and 5% of the mesoporous oxide matrix mass.

5. Catalyst according to claim 1, in which said oxide matrix is mesostructured.

6. Catalyst according to claim 1, in which said mesoporous oxide matrix comprises a silicon oxide that has a specific surface area of 100 to 1,200 m.sup.2/g, a mesopore volume of between 0.2 and 1.8 ml/g, and a mesopore diameter of between 4 and 50 nm.

7. Catalyst according to claim 1, also comprising at least one element that is selected from the group that consists of the elements of groups 11 and 12 of the periodic table and mixtures thereof, with the mass of said element representing between 0.5 and 10% of the mass of said mesoporous oxide matrix.

8. Catalyst according to claim 7, also comprising at least the element Zn, the mass of said element representing between 0.5 and 10% of the mass of said mesoporous oxide matrix.

9. A process for the conversion of a feedstock that comprises at least ethanol into butadiene, comprising contacting said feedstock with a catalyst according to claim 1 at a temperature of between 300 and 400 C., a pressure of between 0.15 and 0.5 MPa, and a volumetric flow rate of between 0.5 and 5 h.sup.1.

10. The process according to claim 9, in which the temperature is between 320 C. and 380 C.

11. The process according to claim 9, in which the pressure is between 0.15 and 0.3 MPa.

12. The process according to claim 9, in which the volumetric flow rate is between 1 and 4 h.sup.1.

Description

EXAMPLES

Description of the Dry Impregnation Method for the Deposition of Tantalum

[0058] The basic silicic substrate before the impregnation steps is the Davisil grade 636 silica that is produced (SBET500 m.sup.2/g, Vp0.9 ml/g and 7 nm, grain size: 200-500 microns).

[0059] The tantalum pentaethoxide (Ta(OCH.sub.2CH.sub.3).sub.5) (whose quantity is calculated from the Ta content to be deposited on the substrate) is diluted in an ethanol solution (whose quantity is proportional to the pore volume of the silicic substrate). This solution is quickly added drop by drop and mixed with the silicic substrate until wettability of the surface of the latter (dry impregnation) is observed. The solid is then placed in an ethanol-saturated atmosphere for 3 hours, dried at 100 C. for 24 hours. The catalyst is obtained by calcination of the solid that is dried in air at 550 C. for 4 hours.

Description of the Dry Impregnation Method for the Deposition of Other Elements

[0060] The precursor of the element that is to be deposited whose quantity is calculated from the content of the element that is to be deposited on the substrate is diluted in an aqueous solution whose quantity is proportional to the pore volume of the silicic substrate. This solution is quickly added drop by drop to the silicic substrate until wettability of the surface of the latter (dry impregnation) is observed. The solid is then placed in a water-saturated atmosphere for 3 hours, dried at 100 C. for 24 hours. The catalyst is obtained by calcination of the solid that is dried in air at 550 C. for 4 hours.

TABLE-US-00001 Element to be Deposited Precursor that is Used Nb C.sub.4H.sub.4NNbO.sub.95H.sub.2O Zr ZrOCl.sub.28H.sub.2O Zn Zn(NO.sub.3).sub.26H.sub.2O Ag AgNO.sub.3 Ca Ca(NO.sub.3).sub.24H.sub.2O Ba Ba(NO.sub.3).sub.2 Mg Mg(NO.sub.3).sub.26H.sub.2O Ce Ce(NO.sub.3).sub.36H.sub.2O La La(NO.sub.3).sub.36H.sub.2O Sn SnCl.sub.3 Cs CsNO.sub.3 In In(NO.sub.3).sub.3 Mo (NH.sub.4).sub.6Mo.sub.7O.sub.244H.sub.2O

Description of the Catalytic Test Unit

[0061] The reactor that is used in the following examples consists of a stainless steel tube that is 20 cm long and 10 mm in diameter. The reactor is first loaded with carborundum and then with the catalyst that is diluted in carborundum and finally with carborundum. The carborundum is inert relative to the feedstock and does not influence the catalytic results; it makes it possible to position the catalyst in the isothermal zone of the reactor and to limit the risks of material and heat transfer problems. The temperature of the reactor is controlled with a tubular furnace with three heating zones. The liquid feedstock (mixture of ethanol and acetaldehyde in a ratio R) is injected via a double-piston HPLC pump. The liquid stream is evaporated in the lines that are heated by a tracer before entering into the reactor and is homogenized by passing into a static mixer. The products that are formed during the reaction are kept in the vapor phase so that they can be analyzed on-line by gas chromatography (PONA and Carboxen 1010 capillary columns) to make possible the most precise identification of the hundreds of products formed. The catalyst is activated in situ under nitrogen at the test temperature. The specific operating conditions are described in the following examples.

Definition of the Terms

[0062] Conversion (% by weight):

[00001]$\mathrm{conversion}=100*\left(1-\frac{\begin{array}{c}\mathrm{mass}.Math..Math.\mathrm{flow}.Math..Math.\mathrm{rate}.Math..Math.\mathrm{of}.Math..Math.\mathrm{exiting}.Math..Math.\mathrm{ethanol}+\\ \mathrm{mass}.Math..Math.\mathrm{flow}.Math..Math.\mathrm{rate}.Math..Math.\mathrm{of}.Math..Math.\mathrm{exiting}.Math..Math.\mathrm{acetaldehyde}\end{array}}{\begin{array}{c}\mathrm{mass}.Math..Math.\mathrm{flow}.Math..Math.\mathrm{rate}.Math..Math.\mathrm{of}.Math..Math.\mathrm{entering}.Math..Math.\mathrm{ethanol}+\\ \mathrm{mass}.Math..Math.\mathrm{flow}.Math..Math.\mathrm{rate}.Math..Math.\mathrm{of}.Math..Math.\mathrm{entering}.Math..Math.\mathrm{acetaldehyde}\end{array}}\right)$

Selectivity (% C):

[0063] [00002]$\mathrm{selectivity}=\frac{\mathrm{mass}.Math..Math.\mathrm{flow}.Math..Math.\mathrm{rate}.Math..Math.\mathrm{of}.Math..Math.\mathrm{carbon}.Math..Math.\mathrm{belonging}.Math..Math.\mathrm{to}.Math..Math.\mathrm{butadiene}.Math..Math.\left(\mathrm{gc}.Math.\text{/}.Math.h\right)}{\begin{array}{c}\mathrm{mass}.Math..Math.\mathrm{flow}.Math..Math.\mathrm{rate}.Math..Math.\mathrm{of}.Math..Math.\mathrm{carbon}\\ \mathrm{belonging}.Math..Math.\mathrm{to}.Math..Math.\mathrm{the}.Math..Math.\mathrm{converted}.Math..Math.\mathrm{feedstock}\end{array}.Math.}$

Example 1: Comparison in the Absence of Tantalum of the Behavior of the Aldolizing Co-Elements in Contact with a Low-Acetaldehyde Feedstock

[0064] In this test example, the ethanol/acetaldehyde ratio of the feedstock is set at 24 mol/mol, the temperature at 350 C., and the pressure at 1.5 bar. For each catalyst, the feedstock flow rate is adjusted to obtain a stable conversion of 45%. The carbon selectivity values are measured at this operating point after a time under load of 2 hours.

TABLE-US-00002 Main Element for the Production Selectivity of of Co- Additional Aldolization According Butadiene Element Element Products to the (% by (% by (% by Butadiene (Crotonaldehyde, Invention Catalyst Weight) Weight) Weight) Selectivity Hexadienals) For A Ta (2%) Zn (1%) 68% 1% Comparison Purposes For A Zn (1%) 31% 17% Comparison Purposes No B1 Ca Zn (1%) 25% 26% (1.5%) No B2 Ba Zn (1%) 24% 35% (1.5%) No B3 Ce Zn (1%) 20% 28% (0.75%) No B4 Mg (2%) Zn (1%) 29% 25% No B5 Sn Zn (1%) 22% 26% (0.75%)
If the co-element (Ca, Ba, Ce, Mg, Sn) is not combined with tantalum, it is not capable, under the test conditions, to produce the butadiene selectively in comparison to the tantalum-based catalyst, but acts primarily as an aldolization catalyst.

Example 2: Comparison in the Presence of Tantalum of the Impact of Co-Elements in Contact with a Low-Acetaldehyde Feedstock with Feedstock Flow Rate Variation

[0065] In this example, the ethanol/acetaldehyde ratio of the feedstock is set at 24 mol/mol, the temperature at 350 C., and the pressure at 1.5 bar. For each catalyst, the feedstock flow rate is adjusted to obtain a stable conversion of 45%. The selectivity values are measured at this operating point after 2 and 48 hours of testing.

TABLE-US-00003 Main Element Initial Loss of for the Aldolizing Additional Additional Butadiene Butadiene According Production of Co-Element Element 1 Element 2 Selectivity Selectivity to the Butadiene (% (% by (% by (% by after 2 after 48 Invention Catalyst by Weight) Weight) Weight)) Weight) Hours Hours For A Ta (2%) Zn (1%) 68% 1 Comparison Purposes Yes F Ta (2%) Ca (0.5%) Zn (1%) 68% 0.3 Yes G Ta (2%) Ca (1.5%) Zn (1%) 66% 0.1 Yes H Ta (2%) Sn (0.25%) Zn (1%) 66% 0.7 Yes I Ta (2%) Sn (0.75%) Zn (1%) 66% 0.4 Yes J Ta (2%) Ce (0.25%) Zn (1%) 65% 0.5 Yes K Ta (2%) Ce (0.75%) Zn (1%) 66% 0.8 Yes L Ta (2%) Mg (0.5%) Zn (1%) 67% 0.2 No M Ta (2%) La (0.75%) Zn (1%) 66% 1.1 No N Ta (2%) In (0.75%) Zn (1%) 59% 1.5 No O Ta (2%) Mo (0.75%) Zn (1%) 60% 1.4 For A Ta (2%) Zn (2%) 67% 2.9 Comparison Purposes Yes P Ta (2%) Sn (0.25%) Zn (2%) 67% 2.2 Yes Q Ta (2%) Ce (0.25%) Zn (2%) 66% 2.3 No R Ta (2%) La (0.25%) Zn (2%) 66% 3.1 No S Ta (2%) La (0.75%) Zn (2%) 65% 3.9 For T Ta (2%) Zn (1%) Cs (0.2%) 69% 1.3 Comparison Purposes Yes U Ta (2%) Ca (0.25%) Zn (1%) Cs (0.2%) 69% 0.6 For V Ta (2%) Ag (2.5%) 67% 6.8 Comparison Purposes Yes W Ta (2%) Ce (0.25%) Ag (2.5%) 66% 3.1 Yes X Ta (2%) Mg (0.75%) Ag (2.5%) 67% 2.8

[0066] This example demonstrates that the presence of suitable co-elements (Ca, Ba, Ce, Mg, Sn), when they are combined with tantalum, makes it possible to keep the butadiene selectivity level at a high and stable value over a longer period of time.

Example 3: Comparison with a Low-Acetaldehyde Feedstock of the Impact of Aldolizing Co-Elements in the Presence of an Element for the Production of Butadiene Other than Tantalum

[0067] In this example, the ethanol/acetaldehyde ratio of the feedstock is set at 24 mol/mol, the temperature at 350 C., and the pressure at 1.5 bar. For each catalyst, the feedstock flow rate is adjusted to obtain a stable conversion of 45%. The selectivity values are measured at this operating point after 2 and 48 hours of testing.

TABLE-US-00004 Main Element for the Production of Aldolizing Co- Additional Loss of According to Butadiene (% by Element (% by Element (% Initial Selectivity the Invention Catalyst Weight) Weight) by Weight) Selectivity in 48 Hours For Y Zr (0.5%) Zn (1%) 63% 1.5 Comparison Purposes No Z Zr (0.5%) La (0.25%) Zn (1%) 62% 1.6 No AA Zr (0.5%) Ce (0.25%) Zn (1%) 61% 1.9 No AB Zr (0.5%) Ce (0.75%) Zn (1%) 62% 1.5 For AC Zr (0.5%) Zn (2%) 63% 1.8 Comparison Purposes No AD Zr (0.5%) Mg (0.25%) Zn (2%) 61% 2.1 For AE Zr (0.5%) Ag (1%) 63% 1.6 Comparison Purposes No AF Zr (0.5%) Sn (0.25%) Ag (1%) 63% 2.2

[0068] Only the tantalum element appeared to benefit from the provision of the aldolizing co-element. When the catalyst contains only one other element for the production of butadiene such as zirconium, the impact of the co-element is zero or negative.

Example 4: Comparison in the Presence of Tantalum of the Impact of Co-Elements in Contact with a Low-Acetaldehyde Feedstock with Temperature Variation

[0069] In this example, the ethanol/acetaldehyde ratio of the feedstock is set at 24 (mol/mol), the beginning test temperature at 350 C., and the pressure at 1.5 bar. For each catalyst, the feedstock flow rate is set to obtain a 45% conversion. Maintaining the conversion is ensured this time by a uniform increase in the temperature of the reactor. The selectivity values are measured after 5 and 72 hours of testing.

TABLE-US-00005 Selectivity Main Element for of the Loss of the Production of Aldolizing Co- Additional Catalyst Selectivity According to Butadiene (% by Element (% by Element (% After 5 After 72 the Invention Catalyst Weight) Weight) by Weight) Hours Hours For A Ta (2%) Zn (1%) 69.3 2.2 Comparison Purposes Yes F Ta (2%) Ca (0.5%) Zn (1%) 66.4 0.2 Yes AG Ta (2%) Sn (2%) Zn (1%) 69.5 1.6 Yes AH Ta (2%) Mg (1.5%) Zn (1%) 67.5 1.4

[0070] This example demonstrates that the presence of suitable co-elements, when they are combined with tantalum, makes it possible to keep the selectivity level at a high and stable value over a longer period of time and temperature.

Example 5: Comparison in the Absence of Tantalum of the Behavior of Aldolizing Co-Elements in Contact with an Acetaldehyde-Rich Feedstock

[0071] In this example, the ethanol/acetaldehyde ratio of the feedstock is set at 2.5 (mol/mol), the temperature at 350 C., and the pressure at 1.5 bar. For each catalyst, the feedstock flow rate is adjusted to obtain a stable conversion of 25%. The carbon selectivity values are measured at this operating point after a time under load of 2 hours.

TABLE-US-00006 Main Element for According the Production of Aldolizing Co- to the Butadiene (% by Element (% by Butadiene Selectivity of Invention Catalyst Weight) Weight) Selectivity Aldolization Products For AI Ta (2%) 65% 4% Comparison Purposes No AJ Sn (1.5%) 25% 31% No AK Ce (0.75%) 18% 36% No AL Mg (1.5%) 24% 40% No AM Ba (0.5%) 10% 60%

[0072] The co-element, if it is not combined with tantalum, is not capableunder the test conditionsof producing butadiene selectively in comparison to the tantalum-based catalyst, but acts primarily as an aldolization catalyst.

Example 6: Comparison in the Presence of Tantalum of the Impact of Co-Elements in Contact with an Acetaldehyde-Rich Feedstock with a Feedstock Flow Rate Variation

[0073] In this example, the ethanol/acetaldehyde ratio of the feedstock is set at 2.5 (mol/mol), the temperature at 350 C., and the pressure at 1.5 bar. For each catalyst, the feedstock flow rate is adjusted to obtain a stable conversion of 44%. The carbon selectivity values are measured at this operating point after a time under load of 2 and 48 hours.

TABLE-US-00007 Main Element for Aldolizing Loss in According the Production of Co-Element Additional Performances Selectivity to the Butadiene (% by (% by Element (% of the Catalyst After 48 Invention Catalyst Weight) Weight) by Weight) After 2 Hours Hours For AN Ta (5%) 71% 0.8 Comparison Purposes Yes AO Ta (5%) Ca (0.1%) 71% 0.2 For AP Ta (0.5%) Nb (0.25%) 74% 0.7 Comparison Purposes Yes AQ Ta (0.5%) Ca (0.1%) Nb (0.25%) 73% 0.2

[0074] This example demonstrates that the presence of suitable co-elements, when they are combined with tantalum, makes it possible to keep the selectivity level at a high and stable value over a longer period of time.

Example 7: Comparison in the Presence of Tantalum of the Impact of Co-Elements in Contact with an Acetaldehyde-Rich Feedstock with Temperature Variation

[0075] In this example, the ethanol/acetaldehyde ratio of the feedstock is set at 2.5 (mol/mol), the temperature at 350 C., and the pressure at 1.5 bar. For each catalyst, the feedstock flow rate is adjusted to obtain a stable conversion of 35%. The selectivity values are measured at this operating point after a time under load of 5 and 72 hours.

TABLE-US-00008 Main Element for According the Production of Aldolizing Co- Performances of to the Butadiene (% by Element (% by the Catalyst Loss in Selectivity Invention Catalyst Weight) Weight) After 5 Hours After 72 Hours For AN Ta (5%) 69% 8.5 Comparison Purposes Yes AO Ta (5%) Ca (0.1%) 70% 4.9

[0076] This example demonstrates that the presence of suitable co-elements, when they are combined with tantalum, makes it possible to keep the selectivity level at a high and stable value over a longer period of time and temperature.