WO2021011567A1

WO2021011567A1 - Process for removing formaldehyde from sugars pyrolysis product mixtures

Info

Publication number: WO2021011567A1
Application number: PCT/US2020/041979
Authority: WO
Inventors: William J. Collins; Emily NEHRKORN; Joshua TERRIAN
Original assignee: Archer Daniels Midland Company
Priority date: 2019-07-18
Filing date: 2020-07-14
Publication date: 2021-01-21

Abstract

A process is described for removing formaldehyde from an aqueous glycolaldehyde composition including water, glycolaldehyde and formaldehyde, and in particular embodiments, from a sugars pyrolysis product mixture including at least water, formaldehyde and glycolaldehyde but frequently also comprising glyoxal, acetol, ethylene glycol, acetic acid and pyruvaldehyde, wherein the process comprises contacting the aqueous glycolaldehyde composition with a cationic ion exchange resin in the calcium form to preferentially retain formaldehyde thereon and provide a reduced formaldehyde content aqueous glycolaldehyde product.

Description

PROCESS FOR REMOVING FORMALDEHYDE FROM SUGARS PYROLYSIS

PRODUCT MIXTURES

TECHNICAL FIELD

[0001] The present invention relates to methods for the removal of formaldehyde as found among the products of sugars pyrolysis, for example, in the pyrolysis of sugars per se or of sugars in biomass to produce browning agents and the like for food product applications or to produce a chemical synthesis feedstock as described, for example, in commonly assigned W02020/028322.

BACKGROUND ART

[0002] Pyrolysis of carbohydrate-containing materials has long been employed for producing browning liquids and flavorants for especially proteinaceous foodstuffs, see, for example, US 5,397,582,“Flavoring and Browning Materials by Pyrolysis of Sugars and Starches” and US 5,135,770,“High Browning Liquid Smoke Composition and Method of Making a High Browning Liquid Smoke Composition”, but has also been described for producing artificial tanning products, see, for example, US 5,252,188,“Process for

Producing Hydroxyacetaldehyde”.

[0003] One of the materials produced by pyrolyzing sugars and starches, however, is formaldehyde. While formaldehyde is typically not present in high concentrations in the product mixtures resultant from pyrolysis or fast pyrolysis of biomass or other

carbohydrate- or starch-containing materials (and parenthetically, hereafter, such hydroxyacetaldehyde (glycolaldehyde) -containing product mixtures will be understood as collectively encompassed within the term“sugars pyrolysis product mixtures”, whether such mixtures result from the pyrolysis of sugars per se, for example, in the form of an aqueous dextrose solution, or whether they result from the pyrolysis of a suitable biomass, for example, a lignocellulosic biomass), yet such formaldehyde is known to pose certain hazards to human health and is undesirable.

[0004] Sugars pyrolysis product mixtures have also been proposed for use as feedstocks in the synthesis of other industrially important chemicals for both food and non food uses. The above-referenced commonly assigned, copending provisional patent application is concerned, for example, with methods for making monoethanol amine (MEA) and/or taurine (2-aminoethanesulfonic acid) from MEA. MEA is a well-known industrial commodity that is used for producing detergents, emulsifiers, polishes, pharmaceuticals, corrosion inhibitors and chemical intermediates, as well as being used in amine gas treating of flue gases and sour natural gas to remove carbon dioxide and hydrogen sulfide, while taurine is a conditional amino acid that has become increasingly popular as a nutritional supplement for humans, with reputed benefits for reducing cardiovascular disease and helping in the treatment of congestive heart failure, decreasing the side effects from

Parkinson’s disease, reducing metabolic syndrome, as an antioxidant in aiding patients with periodontal disease and improving athletic performance, as well as being widely used in animal nutritional products, in fact, being required in dry and wet cat foods in the United States to combat central retinal degeneration and feline dilated cardiomyopathy.

[0005] Unfortunately, in this feedstock context also, formaldehyde in the sugars pyrolysis product mixtures has also been appreciated as problematic. In this regard, US 9,796,649 to Taaming et al. (Taarning) describes processes for using compositions from the pyrolysis of sugars, comprising low molecular weight carbonyl compounds primarily in the form of glycolaldehyde (or hydroxyacetaldehyde) but also including formaldehyde, glyoxal and pyruvaldehyde, for a variety of subsequent chemical transformations including the synthesis of ethylene and propylene glycol through hydrogenation, the synthesis of flexible phenolic carbamido resins, making straight and branched chain oxygenated C4 -alkyl and C4-alkenyl compounds and amines such as ethanolamine (MEA), ethylenediamine and dimethylethanolamine.

[0006] Taaming indicate, however, that formaldehyde is a well-known poison for those subsequent chemical transformations - such as the reductive animation methods by which such amine products may be made - and propose converting formaldehyde in the crude pyrolysis product to formaldehyde acetals and removing the same from the crude pyrolysis product to a sufficient extent that the remaining pyrolysis product can be used in the reductive amination, by reactive distillation in the presence of at least one alcohol and a catalyst.

[0007] In the above-referenced commonly assigned W02020/028322 (hereafter, WO’322), other, simpler methods are described for accomplishing formaldehyde removal. In WO’322, formaldehyde in the crude product from the pyrolysis of dextrose is described as suitably reduced by either carrying out an oxidation in the presence of a catalyst and/or by bringing the crude product in contact with a formaldehyde-scrubbing material that retains formaldehyde from the crude product but leaves glycolaldehyde in the crude product for carrying out a reductive amination thereon to form monoethanolamine, which can then be sulfated as desired to provide 2-aminoethyl hydrogen sulfate ester (AES) and ultimately to provide taurine by sulfonating the AES.

[0008] Still another method proposed for addressing the formaldehyde in sugars pyrolysis product mixtures (though not by removing the formaldehyde per se) is described in US 2018/303137A1 to Piskorz et al., wherein an aqueous solution containing formaldehyde, hydroxyacetaldehyde and other sugar carbonyls (a sugars pyrolysis product mixture) intended for use in browning foodstuffs is treated with an amino acid such as glycine or cysteine, to reduce the formaldehyde in these solutions through a Maillard reaction, without concurrently substantially affecting the glycolaldehyde concentration in the sugars pyrolysis product mixture. The Maillard reaction produces certain red-colored byproducts called melanoidins, and as an optional feature of some embodiments, in certain unspecified instances where the red color is not desired a calcium-form ion exchange resin is used to remove these colored byproducts.

[0009] Whether the sugars pyrolysis product mixtures are intended, as in the just- discussed Piskorz et al. reference, for use in browning or flavoring foodstuffs, or are intended, as in Taaming, to be used as a chemical feedstock for making other products like MEA, approaches as employed in Piskorz et al. or in Taarning which merely produce another material by reaction with the formaldehyde rather than truly removing the formaldehyde are less than satisfactory.

[0010] Methods that would produce a sugars pyrolysis product mixture depleted in formaldehyde and consequently enriched in glycolaldehyde by simply selectively removing the formaldehyde would be desirable, by comparison, in omitting forming other materials in a further step that might also need to be removed by yet another process step.

SUMMARY OF THE INVENTION

[0011] The following presents a simplified summary of the invention in order to provide a basic understanding of some of its aspects. This summary is not an extensive overview of the invention, thus the mention or omission of a particular feature should not be understood as implying, respectively, that the feature is indispensable or of lesser significance. The sole purpose of this summary is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.

[0012] With this understanding, the present invention from one perspective concerns a process for removing formaldehyde from an aqueous glycolaldehyde composition including water, glycolaldehyde and formaldehyde, and in particular embodiments, from a sugars pyrolysis product mixture including at least water,

formaldehyde and glycolaldehyde but frequently also comprising glyoxal, acetol, ethylene glycol, acetic acid and pyruvaldehyde, wherein the process comprises contacting the aqueous glycolaldehyde composition with a cationic ion exchange resin in the calcium form to preferentially retain formaldehyde thereon and provide a reduced formaldehyde content aqueous glycolaldehyde product.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 presents the results of Example 1.

[0014] Figure 2 presents the results of Example 2.

[0015] Figure 3 presents the results of Comparative Example 1.

[0016] The Figures are to be understood to present certain embodiments of the invention to aid in understanding of the principles and reaction chemistry involved, but not to limit the scope of the invention as defined in the appended claims.

DETAILED DESCRIPTION OF EMBODIMENTS

[0017] As used in this application, the singular forms“a”,“an” and“the” include plural references unless the context clearly indicates otherwise. The term“comprising” and its derivatives, as used herein, are similarly intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. This understanding also applies to words having similar meanings, such as the terms“including”,“having” and their derivatives. The term“consisting” and its derivatives, as used herein, are intended to be closed terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but exclude the presence of other unstated features, elements, components, groups, integers, and/or steps. The term“consisting essentially of’, as used herein, is intended to specify the presence of the stated features, elements, components, groups, integers, and/or steps, as well as those that do not materially affect the basic and novel characteristic(s) of stated features, elements, components, groups, integers, and/or steps. Terms of degree such as“substantially”,“about” and“approximately” as used herein mean a reasonable amount of deviation of the modified term (beyond that degree of deviation understood by the precision (significant figures) with which a quantity is expressed) such that the end result is not significantly changed. These terms of degree should be construed as including a deviation of at least plus or minus five (5) percent from the stated value, provided this deviation would not negate the meaning of the term modified.

[0018] Where specific numerical values are used to quantify certain parameters relating to the invention without an accompanying term of degree, and where the specific numerical values are not expressly part of a numerical range, it will be understood that each such specific numerical value provided herein is to be construed as providing literal support for a broad, intermediate and narrow range of values for the parameter in question. The broad range shall be the numerical value plus and minus 60 percent of the numerical value, rounded to two significant digits. The intermediate range shall be the numerical value plus and minus 30 percent of the numerical value, rounded to two significant digits, while the narrow range shall be the numerical value plus and minus 15 percent of the numerical value again to two significant digits. Further, these broad, intermediate and narrow numerical ranges should be applied not only to the specific values, but also to the differences between these specific values. Thus, if the specification describes a first pressure of 110 psia for a first stream and a second pressure of 48 psia (a difference of 62 psia) for a second stream, the broad, intermediate and narrow ranges for the pressure difference between these two streams would be 25 to 99 psia, 43 to 81 psia, and 53 to 71 psia, respectively.

[0019] Where the present description uses numerical ranges to quantify certain parameters relating to the invention, it will be similarly understood that these ranges are to be construed as providing literal support for claim limitations that only recite the lower value of the range as well as claim limitations that only recite the upper value of the range.

[0020] Unless otherwise indicated, any definitions or embodiments described in this or in other sections are intended to be applicable to all embodiments and aspects of the subjects herein described for which they would be suitable according to the understanding of a person of ordinary skill in the art.

[0021] As indicated above, the present invention concerns a process for removing formaldehyde from an aqueous glycolaldehyde composition including water, glycolaldehyde and formaldehyde, comprising contacting the aqueous glycolaldehyde composition with a cationic ion exchange resin in the calcium form to preferentially retain formaldehyde thereon and provide a reduced formaldehyde content aqueous glycolaldehyde product. An aqueous mobile phase is preferably employed, which can be simply water (deionized water) or an aqueous solution of a water-soluble calcium salt, for example, calcium nitrate, as shown in the examples below. The aqueous calcium nitrate solution was observed to provide a nominally better separation of the formaldehyde from a sugars pyrolysis product mixture and could be used as well for regenerating the resin from time to time, so may be more preferred as the aqueous mobile phase as compared to deionized water. The use of an aqueous mobile phase lends itself to contacting the cationic ion exchange resin at a temperature of less than the temperature at which water would boil and cause bubbles in the resin be, for example, a temperature of less than 100 degrees Celsius. A preferred temperature range for operating the resin bed would be from 50 to 100 degrees Celsius, more preferably would be from 70 to 90 degrees Celsius and most preferably would be in the 80 to 90 degrees Celsius range.

[0022] Preferably, by means of the inventive process, at least 75 percent of the formaldehyde in a sugars pyrolysis mixture will be retained in a formaldehyde-rich, retentate fraction, though preferably at least 80 percent of the formaldehyde in a sugars pyrolysis mixture will be retained in the formaldehyde-rich fraction, more preferably at least 85 percent of the formaldehyde will be segregated in the formaldehyde-rich fraction and most preferably at least 95 percent of the formaldehyde will be segregated in the formaldehyde-rich fraction.

[0023] Similarly, at least 75 percent of the glycolaldehyde in the same sugars pyrolysis product mixture will be captured in a glycolaldehyde-rich, permeate fraction, preferably at least 80 percent of the glycolaldehyde will be captured in the glycolaldehyde- rich fraction, more preferably at least 85 percent of the glycolaldehyde will be present in the glycolaldehyde-rich fraction and still more preferably at least 95 percent of the glycolaldehyde will be captured in the glycolaldehyde-rich fraction.

[0024] Further separations may be undertaken on the glycolaldehyde-rich fraction to isolate additional compounds as may be deleterious, for example, in a subsequent use of the glycolaldehyde-rich fraction as a feedstock for chemical synthesis. Feedstock applications wherein formaldehyde particularly is undesirable have already been mentioned, for example, in regard to the aforementioned commonly assigned WO’ 322 published application and in regard to Taaming for making ethylene glycol and the like, but other syntheses have been proposed or are contemplated wherein one or more of these additional compounds - glyoxal, pyruvaldehyde and acetol being most significantly present - might be undesirable.

[0025] Continuous industrial-scale adsorption processes are well known for their efficiency. The operation of a continuous countercurrent moving bed chromatographic apparatus in particular enhances the mass transfer driving force, allowing higher processed throughput for a given quantity of adsorbent and a more complete separation of desired components as compared to traditional batch elution chromatography. Nevertheless, in this countercurrent mode of operation both fluid and solid phases must be in motion. The movement of the solids presents considerable technical problems, however, including erosion of the adsorbent (causing fines leading to high pressure drops) and equipment abrasion. Because of these difficulties, simulated moving bed chromatographic systems have been developed wherein the solid adsorbent is kept static but a periodic one-column shift is performed of all inlet as outlet streams in the direction of the fluid flow. In this manner, an apparent or simulated countercurrent movement of the solid is created relative to the fluid flow. Such simulated moving bed chromatographic systems are widely used in a number of industries and for a variety of applications, and are therefore the preferred approach for implementing a process according to the present invention.

[0026] A detailed treatment of simulated moving bed chromatographic systems, their design and operation need not be undertaken herein, as these systems are in use and well- known; nevertheless, those skilled in the art may find additional information as desired in the open literature, for example, in Gomes and Rodrigues, “Simulated Moving Bed Chromatography: From Concept to Proof-of-Concept”, Chemical Engineering Technology, vol. 35, No. 1, pp 17-34 (2011), and will be guided by the examples described below.

[0027] The following, non-limiting examples of features and combinations of features addressed above collectively further illustrate the present invention:

[0036] Experimental - Examples 1 and 2, and Comparative Example 1

[0037] Initially, a number of ion exchange resins were evaluated for enabling the preparation of a formaldehyde-rich fraction and a glycolaldehyde-rich fraction from a sugars pyrolysis product mixture containing formaldehyde and glycolaldehyde but characteristically containing also glyoxal, pyruvaldehyde and acetol, most often using H⁺ as the counter-ion, at temperatures ranging from ambient (about 25 degrees Celsius) to 80 degrees Celsius. Water and 5mM sulfuric acid solutions were tried as the mobile phase in these evaluations. The resins tested included: DOWEX® MAC-3 macroporous weakly acidic cation exchange resin in an H⁺ form (The Dow Chemical Company);

AMBERLYST® 35M polymeric strongly acidic cation exchange resin, EE form (The Dow Chemical Company); DIAION® USK104 gel-type, low crosslink-density strongly acidic cation exchange resin, EE form (Mitsubishi Chemical Corporation); INDION® 740H macroporous strongly acidic cation exchange resin, H⁺ form (Ion Exchange (India) Limited, Mumbai, India); PUROLITE® A110 polystyrenic macroporous weak base anion exchange resin, primary amine functionalized (Purolite Corporation); and CHROMALITE® PCR- 560 Na⁺ form resin (Purolite Corporation, Bala Cynwyd, PA). None provided a clear separation of formaldehyde from the glycolaldehyde in these sugars pyrolysis product mixtures.

[0038] Then a 100 mL volume of CHROMALITE® PCR-560 polystyrene crosslinked with divinylbenzene gel, sulfonic acid-functional strong acid cation ion exchange resin in a Ca²⁺ form was loaded into a #15 double-walled chromatography column. The resin was slurry-loaded after being thoroughly rinsed with the mobile phase (deionized water in one trial, 0.1M calcium nitrate in a second trial) to remove any contaminating compounds that might have been present. A glycol heater was attached to the column, and the column was allowed to reach 80 degrees Celsius, at which point the mobile phase liquid was drained from the column until level with the resin. 250 pL of product from the pyrolysis of a dextrose solution, containing 13.88 weight percent of glycolaldehyde, 1.32 weight percent of formaldehyde as well as trace to very small amounts of glyoxal, pyruvaldehyde and acetol was loaded on top of the resin, taking care not to disturb the resin bed. Mobile phase was again drained until the glycolaldehyde was level with the top of the resin bed; additional mobile phase was then manually re-added using a pipette, taking care not to disturb the resin bed. The column was connected to a peristaltic pump set at a 3 mL/min flow rate, and to an autosampler running a 30 second sample collection window. The column was allowed to run until 135mL of sample was collected in the form of ninety distinct samples of 1.5 mL each. To identify glycolaldehyde and formaldehyde in the fractions, the samples were collected and run as-is on an Agilent HPLC with RID, H⁺ column and a 5 mM sulfuric acid mobile phase.

[0039] The results are displayed in Figures 1 and 2, and demonstrate the effectiveness of the resin to separate a sugars pyrolysis product mixture into a

formaldehyde -rich fraction and a glycolaldehyde-rich fraction. By the end of the first trial, approximately 90 percent of the formaldehyde present in the sugars pyrolysis product mixture processed through the resin was recovered in the formaldehyde-rich fraction, and approximately 90 percent of the glycolaldehyde in the sugars pyrolysis product mixture was recovered in the glycolaldehyde-rich fraction. By the end of the second trial using the 0.1M calcium nitrate solution as the mobile phase, generally 95 percent of the formaldehyde present in the sugars pyrolysis product mixture processed through the resin was recovered in the formaldehyde-rich fraction, and 95 percent of the glycolaldehyde in the sugars pyrolysis product mixture was recovered in the glycolaldehyde-rich fraction.

[0040] To verify the role of Ca²⁺ counterions in the process, the resin was then converted to its Na⁺ form using first 10 percent by weight of hydrochloric acid to convert the resin to its H⁺ form, then treating the resin with sodium chloride to convert the resin to its Na⁺ form. A repeat of the same procedure as followed for Examples 1 and 2 provided no real separation of the formaldehyde from the glycolaldehyde, however, and no

formaldehyde -rich fraction or glycolaldehyde-rich (and formaldehyde-poor) fraction was produced. The results of this comparative experiment are shown in Figure 3.

Claims

CLAIMS What is claimed is:

1. A process for removing formaldehyde from an aqueous glycolaldehyde composition including water, glycolaldehyde and formaldehyde, comprising contacting the aqueous glycolaldehyde composition with a cationic ion exchange resin in the calcium form to preferentially retain formaldehyde thereon and provide a reduced formaldehyde content aqueous glycolaldehyde product.

2. The process of claim 1, wherein water or an aqueous solution of a water-soluble calcium salt is used as the mobile phase to provide a glycolaldehyde-rich permeate fraction and a formaldehyde-rich retentate fraction, and the process is carried out at a temperature of from 50 to 100 degrees Celsius.

3. The process of claim 2, wherein the process is carried out at a temperature of from 70 to 90 degrees Celsius.

4. The process of claim 3, wherein the process is carried out at a temperature of from 80 to 90 degrees Celsius.

5. The process of any of claims 1 - 4, wherein by means of contacting a quantity of the aqueous glycolaldehyde composition with a quantity of the cationic exchange resin over time, at least 75 percent of the formaldehyde present in the quantity of the aqueous glycolaldehyde composition so processed is removed into the

formaldehyde -rich retentate fraction.

6. The process of claim 5, wherein by means of contacting a quantity of the aqueous glycolaldehyde composition with a quantity of the cationic exchange resin over time, at least 80 percent of the formaldehyde present in the quantity of the aqueous glycolaldehyde composition so processed is removed into the formaldehyde-rich retentate fraction.

7. The process of claim 5, wherein by means of contacting a quantity of the aqueous glycolaldehyde composition with a quantity of the cationic exchange resin over time, at least 85 percent of the formaldehyde present in the quantity of the aqueous glycolaldehyde composition so processed is removed into the formaldehyde-rich retentate fraction.

8. The process of claim 5, wherein by means of contacting a quantity of the aqueous glycolaldehyde composition with a quantity of the cationic exchange resin over time, at least 95 percent of the formaldehyde present in the quantity of the aqueous glycolaldehyde composition so processed is removed into the formaldehyde-rich retentate fraction.

9. The process of any of claims 1-4, wherein by means of contacting a quantity of the aqueous glycolaldehyde composition with a quantity of the cationic exchange resin over time, at least 75 percent of the glycolaldehyde present in the quantity of the aqueous glycolaldehyde composition so processed is removed into the

glycolaldehyde-rich permeate fraction.

10. The process of claim 9, wherein by means of contacting a quantity of the aqueous glycolaldehyde composition with a quantity of the cationic exchange resin over time, at least 80 percent of the glycolaldehyde present in the quantity of the aqueous glycolaldehyde composition so processed is removed into the glycolaldehyde-rich permeate fraction.

11. The process of claim 9, wherein by means of contacting a quantity of the aqueous glycolaldehyde composition with a quantity of the cationic exchange resin over time, at least 85 percent of the glycolaldehyde present in the quantity of the aqueous glycolaldehyde composition so processed is removed into the glycolaldehyde-rich permeate fraction.

12. The process of claim 9, wherein by means of contacting a quantity of the aqueous glycolaldehyde composition with a quantity of the cationic exchange resin over time, at least 95 percent of the glycolaldehyde present in the quantity of the aqueous glycolaldehyde composition so processed is removed into the glycolaldehyde-rich permeate fraction.

13. The process of any of claims 1-4, carried out by simulated moving bed chromatography.