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US-12624373-B2 - Process for producing anhydrosugar(s) from lignocellulosic biomass

US12624373B2US 12624373 B2US12624373 B2US 12624373B2US-12624373-B2

Abstract

The present disclosure relates to a process for producing anhydrosugar(s) from lignocellulosic biomass. In particular, the present disclosure relates to a process for producing anhydrosugar(s) from lignocellulosic biomass by pre-treating the lignocellulosic biomass by contacting it to either an acid or an acidic solution to obtain a pretreated lignocellulosic biomass and subjecting the pretreated lignocellulosic biomass to active pyrolysis followed by condensation to obtain the anhydrosugar(s) in high yield. Further, the present disclosure encompasses utilizing the food organic waste, date pits biomass for production of anhydrosugar(s), Levoglucosan in high yield.

Inventors

  • Labeeb Ali
  • Mohammednoor Al Tarawneh
  • Ayesha ALAM

Assignees

  • UNITED ARAB EMIRATES UNIVERSITY

Dates

Publication Date
20260512
Application Date
20240912

Claims (20)

  1. 1 . A process for producing one or more anhydrosugars from lignocellulosic biomass containing minerals including alkali and/or alkaline earth metal (AAEM) comprising: pre-treating the lignocellulosic biomass by contacting it to either an acid or an acidic solution to reduce the concentration of minerals including the alkali and/or alkaline earth metal (AAEM), followed by washing and drying to obtain a pretreated lignocellulosic biomass; and subjecting the pretreated lignocellulosic biomass to active pyrolysis followed by condensation, wherein the active pyrolysis is carried out in a reactor, wherein the reactor temperature is ramped up at a rate of about 10° C. per minute, and wherein said active pyrolysis is carried out at a temperature in a range of from about 300° C. to about 500° C.
  2. 2 . The process of claim 1 , wherein the one or more anhydrosugars is Levoglucosan.
  3. 3 . The process of claim 1 , wherein the lignocellulosic biomass is one or more ground date-pits or date palm seeds.
  4. 4 . The process of claim 2 , wherein the lignocellulosic biomass is one or more ground date-pits or date palm seeds.
  5. 5 . The process of claim 4 , wherein: the acid is sulfuric acid or nitric acid, and the acidic solution is a sulfuric acid solution or a nitric acid solution.
  6. 6 . The process of claim 1 , wherein the acid is a mineral acid selected from the group consisting of sulfuric acid, nitric acid, phosphoric acid, hydrochloric acid, and mixtures thereof, and the acidic solution is selected from the group consisting of a sulfuric acid solution, a nitric acid solution, a phosphoric acid solution, a hydrochloric acid solution, and mixtures thereof.
  7. 7 . The process of claim 1 , wherein the lignocellulosic biomass is contacted with either an acid or an acidic solution by stirring at a room temperature 25° C.-30° C. for a period of about 1 hour.
  8. 8 . The process of claim 1 , wherein the acidic solution has a pH ranging from 2 to 3 in a 1 mM solution.
  9. 9 . The process of claim 1 , wherein the washing is carried with ion-exchanged water to remove the residual acid.
  10. 10 . The process of claim 1 , wherein the active pyrolysis is carried out in the presence of an inert atmosphere.
  11. 11 . The process of claim 1 , wherein the active pyrolysis is carried out in a reactor selected from the group consisting of a flow reactor, a tubular reactor, or hydrothermal synthesis reactor, and an autoclave.
  12. 12 . The process of claim 5 , wherein: the pre-treating comprises agitating the one or more ground date-pits or date palm seeds by agitating it to the acid or acidic solution to reduce the concentration of minerals including the alkali and/or alkaline earth metal (AAEM) followed by washing with ion-exchanged water and drying to obtain a pretreated one or more date-pits or date palm seeds as the pretreated lignocellulosic biomass; and the active pyrolysis is carried out in a flow reactor in the presence of an inert atmosphere, and the desired temperature is maintained isothermally for 10 minutes.
  13. 13 . The process of claim 12 , wherein the acid or acidic solution is a 1 molar sulfuric acid solution.
  14. 14 . The process of claim 12 , wherein the acid or acidic solution is a 3 molar sulfuric acid solution.
  15. 15 . The process of claim 12 , wherein the acid or acidic solution is a 1 molar nitric acid solution.
  16. 16 . The process of claim 12 , wherein the acid or acidic solution is a 3 molar nitric acid solution.
  17. 17 . The process of claim 1 , wherein the pretreating reduces the concentration of minerals including the alkali and/or alkaline earth metal (AAEM) by at least 74%.
  18. 18 . The process of claim 2 , wherein the process provides a yield of Levoglucosan greater than 35%.
  19. 19 . The process of claim 5 , wherein the process provides a yield of Levoglucosan greater than 70%.
  20. 20 . The process of claim 1 , without employing any catalyst.

Description

TECHNICAL FIELD The present disclosure relates to the field of chemical sciences. In particular, the present disclosure relates to a process for producing anhydrosugar(s) from lignocellulosic biomass by pre-treating the lignocellulosic biomass by contacting it to either an acid or an acidic solution and subjecting the pretreated lignocellulosic biomass to active pyrolysis followed by condensation to obtain the anhydrosugar(s) in high yield. BACKGROUND Anhydrosugar(s), particularly Levoglucosan (LG) also known as (1,6-anhydro-D-glucopyranose) holds significant potential in the chemical industry for synthesizing polymers, medicines, and plastics, and it can act as a substitute for materials like sorbitol. Large quantities of LG are generated through the thermal decomposition of carbohydrates at approximately 350° C., including processes like pyrolysis, gasification, and combustion. LG is one of the main components obtained via the pyrolysis product of raw lignocellulose. LG is often considered among the top candidates in the list of biomass-derived compounds that could be utilized as platform chemicals in the production of high-end products. Particularly, LG derived from lignocellulose via cost-effective pyrolysis at scale shows promise as a fermentable sugar for biofuels and other compounds. Utilizing biomass resources is essential for gradually diminishing reliance on fossil fuels and mitigating their environmental impacts. One of the most pressing challenges is reducing greenhouse gas emissions to combat global warming and decrease carbon footprints. Hence, developing sustainable energy systems centred around renewable biomass is crucial to bridging the energy consumption gap and addressing environmental issues linked to fossil fuels. Currently, biomass serves as the primary repository of carbon-based compounds. Noteworthy among the platform chemicals derived from biomass is 1,6-anhydro-D-glucopyranose, commonly known as levoglucosan (LG). Lignocellulosic biomass, as the primary carbon source, forms the basis of the biorefinery concept. Levoglucosan, also known as 1,6-anhydro-P-D-glucopyranose (LG), is a crucial sugar derivative and platform chemical generated primarily during cellulose pyrolysis. Food organic waste has received less attention in the selective formation of LG as a prominent platform, despite its importance as a biomass category in regions like the Middle East. Date pits, in particular, represent a notable example of food organic waste. Date pits are a significant type of biomass waste found globally. The date seed is an interesting non-woody material, constituting about 10% of the date fruit, with a small cylindrical embryo embedded in a horny endosperm of cellulose and hemicellulose. Despite their high fiber content, date seeds are still considered as an unwanted waste and are discarded or used as animal feed after the date meat is consumed. Middle Eastern and North African countries are major producers of date palms, generating over 1 million tons of date seeds annually. These seeds can serve as an alternative source of cellulosic fibers and other valuable chemicals like maltol. The existing prior art methods are associated with problems such as low yield, usage of catalyst and being expensive. Typically, LG yield from lignocellulose pyrolysis is lower compared to pure cellulose, necessitating pretreatment to optimize cellulose conversion. Thus, the present invention targets the utilization of a substantial volume of unused date waste, particularly prevalent in Middle Eastern and North African countries where date palms yield over 1 million tons of date seeds annually. The present invention aims to yield various valuable chemicals, including LG, through thermal treatment (pyrolysis) of pre-treated date pits for LG production. The primary objective of pretreatment is to remove alkali/alkaline earth metals (AAEMs) and demineralize biomass, which enhances carbohydrate yield or LG yield and improves bio-oil quality. Moreover, the pre-treatment methods used in the present study aimed to enhance unoxygenated hydrocarbon production suitable for transportation fuels. The research involved extracting isolated cellulose using hot water or various concentrations of acids or acid solutions, particularly sulphuric acid or sulphuric acid solution or nitric acid or nitric acid solution. To date, no research has achieved a 72% yield of LG through thermal treatment (pyrolysis) of date pits while also eliminating oxygenated components to enhance the quality of the produced bio-oil without employing any catalyst. The present method addresses the aforesaid limitations associated with existing methods and provides a cost-effective process employing date-pit unused waste resulting in high yield of various valuable chemicals, including LG without the usage of a catalyst. To increase levoglucosan yield from date pits, pre-treatment involving washing crushed date pits with various concentrations of H2SO4 acid or