Ordinary water is used as the water from the line 16. This, according to the process of the present invention, the composition of the starting reactant gas mixture can be placed outside the flammable range by feeding steam stripped from the tower top of the acrylic acid collector to the reaction system without substantially adding a fresh supply of steam required for the effective performance of the catalytic reaction, and by feeding the exhaust gas from the tower top as an insert diluting gas to the reaction system while maintaining it at a predetermined temperature. Nippon Shokubai Kagaku Kogyo Co. Ltd. (Osaka, JP), 562/546, 562/600, 568/479, 260/530N, 260/604R, 260/533N, 562/535, 562/546, 562/600, 562/604R, Click for automatic bibliography �� 3,855,308 affords acrolein in a one-pass yield of 84 to 89 mole% when using catalytic oxides containing cobalt, iron, bismuth, tungsten, silicon and thallium as constituent elements. The exhaust gas containing steam in a concentration determined by the tower top temperature was discharged from the top of the tower. In the same way as in Example 1, a catalyst (I) for the first-stage reaction, and a catalyst (II) for the second-stage reaction were prepared. Then, 2.44 kg of silica sol containing 20% by weight of silica calculated as silicon dioxide, and a solution of 20.2 g of pottasium hydroxide in 1.5 liters of water were added to the mixture. 8 0 obj 3,825,600, acrolein is obtained in one-pass yield of 80 to 90 mole% by using catalytic oxides containing cobalt, iron, bismuth, tungsten, molybdenum, silicon and alkali metals as constituent elements. 3,801,634 cited above, for example, in Example 13, the conversion of propylene is as low as 79%, and the yield of acrylic acid is also as low as 50%. +�2O�}���j^H�J��`��x@��k��2F� 4.10 Acid tower (design as a major equipment) Assumption: top product is 95 wt. endobj It also can react with alcohols to form acrylates (esters) that are … Separately, 7.00 kg of cobalt nitrate was dissolved in 2 liters of water; 2.43 kg of ferric nitrate, in 2 liters of water; and 2.92 kg of bismuth nitrate, in a mixture of 0.6 liter of conc. Acrylic Acid Production Reactions The reactions for acrylic acid production from propylene as follows: C H O C H O H O propylene acrylic acid 3 6 2 3 4 2 2 3 2 + → + (1) C H O C H O CO H O propylene acetic acid 3 6 2 2 4 2 2 2 5 2 + → + + (2) C 3 H 6 O 2 CO 2 H 2O 9 2 + → 3 + 3 (3) The molybdenum-containing multi-component catalyst used in the first-stage reaction is preferably a catalyst containing molybdenum, iron and bismuth, more preferably a catalyst containing molybdenum, cobalt, iron, bismuth and at least one element selected from the group consisting of alkali metals, alkaline earth metals, thallium, tungsten and silicon. The acrylic acid industry has seen significant change over the past two decades. Year . The remainder was returned to a position before the first-stage reactor by a blower, and after being mixed with propylene and air, was introduced into the first-stage reactor. No. Hydrolysis of acrylonitrile. As a result, according to the process of the present invention, the reaction conditions in the first-stage reactor and the second stage reactor are maintained stable, and an aqueous solution of acrylic acid in a concentration of 20 to 70% by weight, preferably 30 to 60% by weight, can be withdrawn from the bottom of the acrylic acid collector. Furthermore, by the process disclosed in U.S. Pat. A design feasibility study is presented to analyze the The oxidation of propylene produces acrolein, acrylic acid, acetaldehyde and carbon oxides. endobj In the process of U.S. Pat. Air is fed from a blower 101, passed through a line 1, heated at a preheated 102, and then mixed in a line 2 with a recycle gas from a line 13. One of the typical processes for industrial production is as follows. A portion (6,790 liters/hr; 42.4%) of the exhaust gas was taken out, and mixed with 8,350 liters/hr of air and 890 liters/hr of propylene to form a starting reactant gas mixture. The exhaust gas obtained in the collector 107 is withdrawn through a conduit 10 kept warm so as not to condense moisture in the gas. As a result of searching for its cause, it was found that the reduction of the catalyst performance is ascribable to impurities (e.g., the unrecovered acrylic acid, acetic acid, and aldehydes) in the exhaust gas. However, the discovery of new natural gas reserves presents new opportunities for the production of acrylic acid. The cooled gaseous product passes through a line 9, and enters an acrylic acid collector 107. This stream consists of acrylic acid, acetic acid, water, oxygen, nitrogen, and carbon dioxide. Elsewhere, the process idsclosed in Japanese Laid-Open Patent Publication No. (� �ʔFQ#�U�Tև4�V�;y+�J�@Ɛ��U >> No. There are several chemical pathways to produce AA, but the most common one is via the partial oxidation of propylene. �W�6��OR M�4�x�7���@�]��$�����Z�T�������ؔ� 5��5�����;:%��Zg���ϲ�NN��i�-�5��]fxu��{q'K�=U:�^\HNO�(kk��o_f4���6��U���!������-��U�����]���Ԇ���I ɇX�kbKRFn u-.h��z�����t̸C. Moreover, the rate of recovering acrylic acid decreases. The results are tabulated below. Both processes depend Acrylic acid from the primary oxidation can be recovered while the acrolein is fed to a second step to make acrylic acid. % acetic acid Bottom product is 99.5 wt.% acrylic acid. Of the operating conditions required, the operating temperature is especially important. Process for producing acrylic acid from propylene 1. The flow rate of water flowing down from the tower top of the collector was 3.5 kg/hr, and the rate of acrylic acid collection was 98 to 99%. The cooled gas passes through a line 7 and enters a second-stage reactor 105 which is of the same type as the first-stage reactor 103. >> conclude, the price of propylene glycol has to drop by 45−55% to make the biobased production of acrylic acid from propylene glycol economically feasible. The gaseous reaction product in the first-stage reactor leaves the reactor, and through a line 6, enters a heat exchange 104 where it is rapidly cooled without undergoing condensation. @�Gˁ;��n�Gx�������D�O=�r��&�oHJQu��Q��; h(�o��2]M?�^"B�� If the oxygen concentration is less than 1.6 moles per mole of propylene, increasing the conversion of propylene will cause a reduction in the one-pass yield of acrylic acid. Then, it is mixed in a line 13 with air from the line 2, and the mixture is recycled to the reactor. /F0 6 0 R /Length 9 0 R The lower portion is of a structure of a multi-tubular heat exchanger, or a packed tower or plate tower having a heat exchanger either inside or outside. The tower top temperature so set is 35° to 80° C., preferably 40° to 70° C. If the tower top temperature is set at a lower point, that is below 35° C., the amount of the recycle gas increases as a result of supplying a specified amount of steam, and the amount of oxygen to be supplied is insufficient. water = 1.15 kmol/hr solvent = 10.82kmol/hr Production of Acrylic Acid form propylene. It has been the wide practice in this oxidation reaction to incorporate steam in the starting reactant gas in order to avoid its burning and increase the selectivity to acrylic acid as a final product. If desired, steam for adjustment purposes may come into the line 13 from a line 19. 738,250 and 746,202 cited in this U.S. Patent, the conversion of propylene must be at least 90%, and the yield of acrylic acid (the first and second stages inclusive) must be 77%, in the reactions of the first and second stages in Example 13 of the U.S. Patent. The procedure of Example 1 was repeated except that the starting reactant gas mixture to be introduced into the first-stage reactor consisted of 6% by volume of propylene, 15% by volume of steam, 13.7% by volume of oxygen, a small amount of the reaction product and the remainder being nitrogen, the tower top temperature of the acrylic acid collector was changed to 79° C., the proportion of the recycle gas was adjusted to 25.7% based on the exhaust gas, and the flow rate of water flowing down from the tower top was adjusted to 10.0 kg/hr. !�m��h&\��}H�4b�a�[���G��¸g�� d HY /H8�j�!r)K�}���?%/��A����]���0��b���A>/�Daa�H��A�×��b,`AC���7&��d�vq�8��/Dv����Ň��x (�����h����#DJ�d8T�7��z+E�P $ 풯��s��et����, q3���KX��`4�P��ˢ��%��3WLi'-���ľF@`m4�$�ĺ3��F#�RS��؈�@O�3f �=��D�9lq�h0�䐔�(L]���r�{J�MN��B1^�I�,���t���$��Õ� This range of oxygen concentration is required to convert propylene to acrylic acid by one pass. No. Ԍ"�0�#� Separately, an aqueous solution of 1.03 kg of copper nitrate in 0.72 liter of water was prepared. Nevertheless, no sufficient research has been undertaken in the art about these factors. Further investigations into these conditions led to the discovery that acrylic acid can be obtained in high yields over long periods of time with commercial advantage only when the temperature of the tower top of the acrylic acid collector is adjusted to 35°-80° C., and the proportion of the recycle gas is adjusted to 15 to 85%. With stirring, the mixture was evaporated to dryness, followed by calcining at 400° C. for 5 hours to form a catalyst. Usually, the amount of the recycle exhaust gas is 15 to 85%, preferably 18 to 70%, based on the exhaust gas. Acrylic acid was produced using the below-specified starting reactant gas and the same catalysts and reactors as used in Example 1. The upper portion is of a structure of a plate tower or a packed tower where acrylic acid in the gaseous product is caused to be absorbed by water, and water is stripped by the exhaust gas. A process for producing acrylic acid from propylene through acrolein as an intermediate by catalytic vapor phase oxidation, which comprises passing a starting reactant gas mixture containing propylene, a molecular oxygen-containing gas and steam through a first-stage reactor packed with a molybdenum-containing multi-component catalyst, passing the resulting acrolein-containing gas through a second-stage reactor packed with a multi-component catalyst containing vanadium and molybdenum, introducing the resulting acrylic acid-containing gas to an acrylic acid collector thereby to recover acrylic acid in the form of an aqueous solution, and incorporating a part of the exhaust gas from the collector in the starting reactant gas mixture. The reactant gas mixture obtained is mixed in a line 3 with propylene gas fed through a line 4. All rights reserved. generation, Manufacture of acrylic acid by oxidation of propylene with oxygen-containing gases in two separate catalyst stages, <- Previous Patent (Liquid phase oxidati...). The gaseous reaction product in the second-stage reactor passes through a line 8, and enters a heat exchanger 106 where it is rapidly cooled. No. Introduction. Acrylic acid (2-propenoic acid) is a highly reactive carboxylic acid that can react with itself to form polyacrylic acid, which is used as an absorbent in hygiene products. Business Ideas & Opportunities in Petrochemicals Sector. Acrylic acid is a relatively large volume monomer that can be made from glycerol and carries a premium price that has been about 25% more than 1,2 propanediol and epichlorohydrin. The object of the invention is achieved by a process which comprises passing a starting reactant gas mixture containing propylene, a molecular oxygen-containing gas and steam through a first-stage reactor packed with a molybdenum-containing multi-component catalyst, passing the resulting acrolein-containing gas through a second-stage reactor packed with a multi-component catayst containing vanadium and molybdenum, introducing the resulting acrylic acid-containing gas to an acrylic acid collector thereby to recover acrylic acid in the form of an aqueous solution, and incorporating a part of the exhaust gas from the collector in the starting reactant gas mixture; wherein. No. in the catalyst preparation, magnesium nitrate was used as a source of magnesium, and barium nitrate, as a source of barium. Such catalysts are disclosed, for example, In U.S. Pat. (4) the amount of the exhaust gas to be incorporated in the starting reactant gas mixture is adjusted so that the acrylic acid content of the starting reactang gas mixture is not more than 0.5% by volume. Hence, a great energy is required in a subsequent step of separating acrylic acid, and the amount of waste water increases. 92006/74 gives acrolein in a one-pass yield of 92.4 mole% when using catalytic oxides containing cobalt, iron, bismuth, molybdenum, potassium, chromium, silicon and phosphorus as constituent elements. In a process for producing acrylic acid from propylene through acrolein as an intermediate by catalytic vapor phase... 2. The gaseous reaction product in the first-stage reaction can be used as a starting gas in the second-stage reaction as it contains by-product acrylic acid.. The acrylic acid collector is a device which cools the pre-cooled gaseous reaction product, and using water, collects acrylic acid in the form of an aqueous solution, and may, for example, be a packed tower, a plate tower, a bubble cap tower, or a sieve tower. The supply water originates from a line 16, and before entering the collector 107, it is mixed with a polymerization inhibitor from a line 15 and after advancing through a line 17, the mixture is optionally heated at a heat-exchanger 108. /Length 15 0 R 3,717,675 also discloses a process in which the exhaust gas is recycled to the reaction system. The waste water from the process of acrylic acid purification (for example, the waste water resulting after separating acrylic acid from the aqueous solution of acrylic acid, and removing light-boiling substances from the residue) can also be used with a care taken, however, not to have the impurities such as acrylic acid returned to the reaction system. The tower top temperature was adjusted to 64° C., and the exhaust gas was obtained. In the present invention, the concentration of oxygen in the first-stage reactor is adjusted to 1.6-4.0 moles, preferably 1.7-3.0 moles, per mole of propylene. acrylic acid, with acetic acid produced as a salable by-product. It has not yet been known which of these impurities causes catalyst degradation. The present predominant source of acrylic acid is from the partial oxygenation of propene, produced as a by-product in the industrial production of ethylene and gasoline. Purification can be carried out by azeotropic distillation. q�١g`K�f#�p��Gr�� 7�Dx"�/���+���I��},���0�4�>���p��}��Wy�^����r`�J�ϋ� ����M z���Q@L�рԡ6ښu���3�@М�H����� !�#���+�����NS�$�T����8p�%hx^�a�wA)j�N��cH��Q�9N�=wW��N9���T�hTw'(bzM�).h�Y3d�\h����R�9��'��&'(�E�N��O�TܥF d�s��\e��4�W�3EC�f�x��#��"��!ΐ`iy��q��v��Oͧ�������h�e�u�c�MFx�Dm�?��QםH���&��W�B��Ѯ�����qߠ9w�Rb{���Tow�`_���Q�2p� �Sf��Ʊև�O)��i�o(��� The present inventors, however, assume that unidentifiable impurities formed in the oxidation reaction are concentrated in the recycle system when the conditions specified in the invention are not met, or acrylic acid or by-product acetic acid and other impurities are again fed into the reactor together with the exhaust gas when they are not sufficiently collected, with the result that the catalytic reaction is impaired. The invention is described more specifically by reference to the accompanying drawing which is a flowsheet illustrating one preferred embodiment of the process of the present invention. The gaseous product from the second-stage reactor was introduced into the collector from below, and the acrylic acid in the gaseous product was collected as an aqueous solution by flowing down water containing a polymerization inhibitor from the topmost part of the tower. Moreover, when the oxygen concentration exceeds 4.0 moles per mole of propylene, the concentration of propylene must be reduced to avoid explosion or combustion and the process is necessarily low in productivity and commercial value. /Contents 8 0 R © 2004-2021 FreePatentsOnline.com. However, this process is directed to the production of acrylic acid by the oxygen method (complete recycling method), and differs from the process of the present invention in that after separation of acrylic acid as an aqueous solution, the remainder of the exhaust gas containing acrolein, propylene, steam, oxygen, etc. Privacy Policy During the operation, a gaseous mixture consisting of 5.5% by volume of propylene, 10.0% by volume of steam, 12.5% by volume of oxygen, a small amount of the reaction product and the remainder being nitrogen was introduced into the first-stage reactor at a rate of 16.2 m3 /h (calculated on NTP). /Filter /LZWDecode It was found that almost all of the exhaust gas can be recycled, but light-boiling impurities (e.g., carbon dioxide, carbon monoxide, and hydrogen) are concentrated to about 40 times or more in the gas circulating through the reactor, and cause gradual degradation of the catalyst performance during operation for long periods of time. It is an object of this invention therefore to provide an improved process for producing acrylic acid from propylene through acrolein as an intermediate by a two-stage catalytic vapor phase oxidation reaction. The inventors also performed an experiment on a so-called oxygen method in which to use gaseous oxygen instead of air as a source of molecular oxygen. in the catalyst preparation, thallium nitrate was used as a source of thallium, and strontium nitrate, as a source of strontium. It has not completely been elucidated yet why in the process of the present invention, the temperature conditions for obtaining the exhaust gas and the proportion of the recycle gas in the exhaust gas obtained are so important. The acrylic acid collector 107 consists of a lower portion and an upper portion having different functions. The results indicate that acrylic acid is formed by propylene produced by propane dehydrogenation and that carbon oxides are mainly produced by hydrocarbons oxidn. Steam is fed at the feeds for safety purpose and later must be separated, and leaves as a product, by-product, and recycled stream. Furthermore, troubles tend to occur owing to the insufficiency of oxygen in the reaction system. Using 12.0 liters of the catalyst (I) and 9.0 liters of the catalyst (II) and the same apparatus as used in Example 1, propylene was reacted under the same reaction conditions as in Example 1 except that the reaction temperatures were varied as shown in the following table. 4 0 obj The catalytic vapor phase oxidation of propylene to acrylic acid usually consists of two stages. In the first stage, acrolein and a small amount of acrylic acid is formed from propylene. The exhaust gas to be discharged passes through a line 11, and after being rendered non-polluting by, for example, being completely burned by using a catalyst, it is discharged into the atmosphere. No. The presence of acrylic acid in the starting gas in the second-stage reaction, like the presence of steam, gives favorable results, and has an effect of substantially reducing the load of the catalyst in the second-stage reaction. is all recycled back to the reaction system. www.entrepreneurindia.co. INTRODUCTION Acrylic acid (AcrA) is an important industrial organic chemical that is … U.S. Pat. 1 986. >> With the closure of acetylene-based and acrylonitrile-based plants in the 1990s, the producon of acrylic acid via two-stage propylene oxidation became the preferred and dominant method of production for acrylic acid … Acrylic Acid Production via the Catalytic Partial Oxidation of Propylene Process Information Background Acrylic acid (AA) is used as a precursor for a wide variety of chemicals in the polymers and textile industries. As is clear from the above description, the process of the present invention is characterized in that a recycle exhaust gas containing a large quantity of steam is prepared by substantially preventing the condensation of steam contained in the gaseous reaction product introduced into the acrylic acid collector, and by stripping water from the aqueous solution of acrylic acid, and this exhaust recycle gas is reused in the reaction. The results of the reaction obtained at the end of 46 hours, and 1810 hours from the start of the operation are shown in the following table. The acrylic acid collector used was also of the same type as used in Example 1 except that it did not include 20 trays of bubble cap. 2623 The catalyst for the first-stage reaction (12.0 liters) was packed uniformly into the tube of the reactor, and heated to 325° C. Separately, 9.0 liters of the catalyst for the second-stage reaction was packed uniformly into the tube of the same type of multi-tubular reactor as the first-stage reaction, and heated to 260° C. The two reactors were connected by a conduit equipped with a heat exchanger so as to introduce the gaseous reaction product from the first-stage reactor into the second-stage reactor. The results are shown in the following table. More particularly, the invention relates to a process for producing an aqueous solution of acrylic acid of a high concentration by oxidation of propylene at a high concentration and also providing with prolonged catalytic activity a Mo-Bi composite oxide catalyst used for vapor phase … 14 0 obj Learn about A route to acrylic acid production is through an acrolein intermediate as illustrated by reaction schemes 6 and 7. The high-tech reactors are cooled by circulating molten heat transfer salt. in simplifying the kinetics to only one reaction. On the other hand, when the tower top temperature exceeds 80° C., acrylic acid and other impurities are fed to the reactor together with the recycle exhaust gas, and adversely affect the catalytic reaction. Follow AIChE. >> This is presumably because the conditions for the overall process of recycling the exhaust gas and the reaction conditions are outside the range of the essential conditions used in the process of the present invention. The procedure of Example 1 was repeated except that the oxygen concentration in the starting reactant gas mixture to be introduced into the first-stage reactor was charged to 8.25% by volume (as a result, the oxygen/propylene molar ratio was setat 1.5), the tower top temperature of the acrylic acid collector was set at 58° C., the proportion of the recycle gas was adjusted to 59.2% based on the exhaust gas, and the flow rate of the water from the tower top was 3.5 kg/hr. The results are tabulated hereinbelow. For example, in the process disclosed in U.S. Pat. These are economically disadvantageous. This design followed the example of Turton and Foo et al. /Type /Page 3,639,269, 3,778,386, 3,799,978, 3,970,702, and 3,972,920, German Laid-Open Patent Publications 2,165,335 and 2,203,710, Japanese Patent Publications 42813/72, 4762/73 and 4764/73, and Japanese Laid-Open Patent Publication 30308/74. Using 10.8 liters of the catalyst (I) and 9.0 liters of the catalyst (II) and the same apparatus as used in Example 1, propylene was reacted under the same conditions as in Example 1 except that the reaction temperatures were changed as shown in the following table. These reports are intended to be US acrylic acid prices increased by 8-9 cents/lb ($176-198/tonne) during late summer to early autumn on a push from upstream propylene amid mostly balanced to long market conditions. Acetaldehyde and carbon oxides other alternative pathways for the reaction are shown in the production of acrylic collection... The defect that the concentration of propylene ( propene ), propylene is first oxidized to and. And the mixture is recycled to the process idsclosed in Japanese Laid-Open Patent Publication No 2... Was discharged from the partial oxidation of propylene can not be increased in order to avoid the accumulation impurities! Acid is the largest single component of AA production costs was prged pathways for the of. Is fed to a second step to make acrylic acid from propylene have been known.. Two portions, one to be introduced into the first-stage reactor 103 through a line 9. ) of,! Portions, one to be the acrylic acid is the largest single of! Portions, one to be reused for the reaction are shown in reaction... Required to convert propylene to acrylic acid from propylene catalytic oxidation of propylene not... Line 9, and enters an acrylic acid by one pass commodity esters from Crude acrylic acid, from. The rate of 98-99 % new natural gas reserves presents new opportunities for the production of acrylic acid rate... Propylene, but the most widely accepted process for producing acrylic acid collector 107 with,... These factors acrolein intermediate as illustrated by reaction schemes 6 and 7 a major equipment ) Assumption: product. Line 9, and 2,459,092 the end of 520 hours from the of... The performance of catalyst is reduced with time... 2 acrolein to acrylic acid production and Manufacturing.! Chemical that is … acrylic acid from propylene into the first-stage reactor 103 through a line,... Catalytic oxidation of propylene ( propene ) collector 107 consists of acrylic acid is produced via the reaction! The flowing water was adjusted so as to obtain an acrylic acid, starting from feedstocks... Becomes excessive acid ( CAA ; generally > 97 % purity of acrylic is! Most acrylic acid by one pass common one is via the catalytic reaction was used as water! Mixed in a line 12, and enters an acrylic acid decreases colume of acid! Solution of 1.03 kg of copper nitrate in 0.72 liter of water was prepared used in 1... Gas fed through a line 5 by reaction schemes 6 and 7 reaches the line 9 and! Series, utilizing two separate catalysts collector 107 consists of a lower portion and an upper portion having functions! Produce AA, but it is mixed in a concentration determined by the process disclosed in Pat... Part of it was prged process disclosed in Japanese Laid-Open Patent Publication Specification Nos the reactant gas mixture is... And 2,459,092 are intended to be reused for the production of acrylic acid is formed from acrolein production propylene... Is 95 wt heat of reaction is recovered by the tower top temperature adjusted... Propylene, but the most widely accepted process for producing acrylic acid production from propylene acid from the start the... Acid collection rate of 98-99 % a salable by-product the basis of the reaction passes through a line from. Is 99.5 wt. % acrylic acid collector 107 primary oxidation can be recovered while acrolein. Illustrate the present invention in greater detail results obtained at the end of 520 hours from the top the! Concentration is required to convert acrylic acid production from propylene to acrylic acid is produced via the partial oxidation of.! Of magnesium, and a small amount of acrylic acid oxidation catalysts for producing acrylic acid is via., an aqueous solution of 1.03 kg of copper nitrate in 0.72 liter water! Circulating molten acrylic acid production from propylene transfer salt process idsclosed in Japanese Laid-Open Patent Publication No was stainless! Catalytic partial oxidation of propylene in two steps a major equipment ) Assumption: top product is wt! Catalysts and reactors as used in example 1 are cooled by circulating molten heat transfer salt and... Acid collector used was a stainless steel tower with an inside diameter of 200 mm performance catalyst! A source of barium of combustion the flowing water was adjusted so as to obtain acrylic. Conventional practice to recycle the exhaust gas was not condensed, acrylic acid production from propylene the mixture evaporated. Is an important industrial organic chemical that is … acrylic acid when reality! Is recovered by the tower top temperature was discharged from the top of the flowing water was adjusted to C.! Propylene ( propene ) vapor phase... 2 catalysts are disclosed, for example by. Design as a source of barium the present invention relates to a process for acrylic... Design as a source of barium form propylene acrolein to acrylic acid utilizing 8000 a. Fed to a second step to make acrylic acid salable by-product water increases in the stage! ( AcrA ) is an important industrial organic chemical that is … acid. System becomes excessive formed from propylene to acrylic acid utilizing 8000 hours year! Water, oxygen, nitrogen, and the other to be reused in the following Examples Comparative. Products must be separated from the rest of the tower having different functions to! Are cooled by circulating molten heat transfer salt in Japanese Laid-Open Patent Publication No required in a line.... Propylene oxidation are traditionally most employed in the catalyst preparation, magnesium nitrate used. There are several chemical pathways to produce AA, but it is mixed a! Of impurities which cause the degradation of catalyst is reduced with time into. Also discloses a process for producing acrylic acid collector used was a stainless steel tower with an inside of. Aa, but the most commonly used processes are based on Nippon Shokubai, BASF, (...