Hydrothermal liquefaction of municipal sewage sludge: Effect of red mud catalyst in ethylene and inert ambiences

Rahman, Tawsif; Jahromi, Hossein; Roy, Poulami; Adhikari, Sushil; Hassani, Ehsan; Oh, Tae-Sik

doi:10.1016/j.enconman.2021.114615

Cited by 51 publications

(27 citation statements)

References 59 publications

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“…The RM-based catalyst was prepared based on our earlier research. 20 In summary, the RM was calcined at 575 °C for four hours before being sieved to get particles with a size range of 106−595 μm. The calcined, sieved RM was activated by reducing at 500 °C for six hours with a gas mixture of 10% hydrogen and 90% nitrogen and then kept in an airtight container for later use.…”

Section: Catalyst Preparationmentioning

confidence: 99%

“…33 Details of the reactor setup are discussed elsewhere. 20 Briefly, a 1.8 L reactor vessel that has a controllable agitator, a PID-controlled electrical heating unit, a pressure gauge, and a J-type thermocouple to monitor the temperature inside the reactor was used. According to the literature, feedstock to water ratio of 1:1.75 was maintained by adding 50 g of shredded and sieved single plastic or plastic mixture with 87.5 g of deionized water inside the reactor.…”

Section: Energy and Fuelsmentioning

confidence: 99%

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Depolymerization of Household Plastic Waste via Catalytic Hydrothermal Liquefaction

Rahman,

Jahromi,

Roy

et al. 2023

Energy Fuels

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An unprecedented use of plastics has caused many environmental issues, and as usual, there is a growing interest in recycling and reusing single-use household plastics. In this work, a mixture of five prominent plastic polymers, as simulated household waste, was depolymerized via the hydrothermal liquefaction (HTL) process using a pretreated red mud catalyst (RM) for the liquid product at 430 ± 20 °C reaction temperature for an average 2 h residence time. The selected plastics were polyethylene terephthalate (PET), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), and polystyrene (PS), which were blended at a ratio of 42, 20, 20, 4, and 14 wt %, respectively, to form a plastic mixture (PM) as a simulated household plastic waste. Additionally, each plastic type was treated individually for control experiments. Among the single plastics, HDPE generated a maximum crude oil yield of 76 wt %, whereas PET produced mainly solid (80 wt %) and gaseous products. The crude oil yield production from noncatalytic reactions followed this trend: HDPE > PS > PP > LDPE. The plastic crude oil possessed 36–92 wt % gasoline-range compounds. Without a catalyst, HDPE decomposed into straight-chain alkanes, whereas PP- and PS-derived products consisted of cyclic compounds. The noncatalytic PM HTL reaction produced 23 wt % liquid crude product and 23 wt % solid from PET. Though the use of a catalyst decreased the single plastic crude yield by 5–60%, it reduced viscosity by 20–80%, minimized acidity by 14–57%, and increased low boiling products (gasoline range) of HTL oil by 5–80%. The use of the RM catalyst increased the crude yield of PM by 63%, decreased solid output from PET by 10%, improved energy recovery by 4.7%, promoted aromatization in PM-derived crudes by 11.4%, and increased the gasoline boiling range compounds by 18.3%. Additionally, the RM catalyst was recycled without significant change in the PM crude yield. This liquefaction study can help in mitigating plastic recycling issues with liquid fuel production.

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Section: Catalyst Preparationmentioning

confidence: 99%

Section: Energy and Fuelsmentioning

confidence: 99%

Depolymerization of Household Plastic Waste via Catalytic Hydrothermal Liquefaction

Rahman,

Jahromi,

Roy

et al. 2023

Energy Fuels

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“…A small body of literature looks at the impact of including clay minerals during HTC of biomasses, sometimes couched in an investigation into clay transformation mechanisms [18]. A growing body of research demonstrates how in situ clay incorporation into hydrothermal processing can shift the oxygen and carbon ratios of the products, producing deoxygenated biocrudes as a result of the clays' Lewis acid and base sites [19][20][21]. Bentonite clay consists of metal oxides, mainly SiO 2 , Al 2 O 3 , Fe 2 O 3 , MgO, Na 2 O, and K 2 O, which provide Brønsted and Lewis acid centers within the clay [22].…”

Section: Introductionmentioning

confidence: 99%

Impact of Bentonite Clay on In Situ Pyrolysis vs. Hydrothermal Carbonization of Avocado Pit Biomass

et al. 2022

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Biofuels produced via thermochemical conversions of waste biomass could be sustainable alternatives to fossil fuels but currently require costly downstream upgrading to be used in existing infrastructure. In this work, we explore how a low-cost, abundant clay mineral, bentonite, could serve as an in situ heterogeneous catalyst for two different thermochemical conversion processes: pyrolysis and hydrothermal carbonization (HTC). Avocado pits were combined with 20 wt% bentonite clay and were pyrolyzed at 600 °C and hydrothermally carbonized at 250 °C, commonly used conditions across the literature. During pyrolysis, bentonite clay promoted Diels–Alder reactions that transformed furans to aromatic compounds, which decreased the bio-oil oxygen content and produced a fuel closer to being suitable for existing infrastructure. The HTC bio-oil without the clay catalyst contained 100% furans, mainly 5-methylfurfural, but in the presence of the clay, approximately 25% of the bio-oil was transformed to 2-methyl-2-cyclopentenone, thereby adding two hydrogen atoms and removing one oxygen. The use of clay in both processes decreased the relative oxygen content of the bio-oils. Proximate analysis of the resulting chars showed an increase in fixed carbon (FC) and a decrease in volatile matter (VM) with clay inclusion. By containing more FC, the HTC-derived char may be more stable than pyrolysis-derived char for environmental applications. The addition of bentonite clay to both processes did not produce significantly different bio-oil yields, such that by adding a clay catalyst, a more valuable bio-oil was produced without reducing the amount of bio-oil recovered.

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“…27 Chemical conversion of such waste into solid, high N content fertilizer materials, on the other hand, has the potential for impactful Available N amount in the US that does not originate from natural gas-derived mineral fertilizers for animal manure, 14,15 food waste of MSW, 16,17 agricultural residues, 18−23 forestry residues, 18,24 and municipal sewage sludge. 25 Uncertainties are provided for the upper and lower values found in the literature.…”

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confidence: 99%

“…Data obtained from USDA Agricultural Marketing Service from 2011 through 2022 and USDA National Agricultural Statistics Service before 2011. (b) Available N amount in the US that does not originate from natural gas-derived mineral fertilizers for animal manure, , food waste of MSW, , agricultural residues, − forestry residues, , and municipal sewage sludge . Uncertainties are provided for the upper and lower values found in the literature.…”

mentioning

confidence: 99%

Role and Responsibility of Sustainable Chemistry and Engineering in Providing Safe and Sufficient Nitrogen Fertilizer Supply at Turbulent Times

Eisa¹,

Ragauskaitė²,

Adhikari³

et al. 2022

ACS Sustainable Chem. Eng.

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certain negative environmental impacts. 45−47 Overall, decisive action is needed to ensure safe and sufficient N fertilizer supply under turbulent times, and sustainable chemistry and engineering have to play a significant role. This is substantiated by the fact that the population is projected to increase to ∼9.8 billion by 2050, while the N-rich protein diet is also expected to increase as 99% of the population growth from 2020 to 2050 is projected to occur in Asia and Africa, currently on a low-protein diet. 48 We hope that this editorial will stimulate and seed creative thinking in obtaining sustainable synthesis routes of efficient and stable N fertilizers from widely available waste, rather than utilizing natural gas.

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Hydrothermal liquefaction of municipal sewage sludge: Effect of red mud catalyst in ethylene and inert ambiences

Cited by 51 publications

References 59 publications

Depolymerization of Household Plastic Waste via Catalytic Hydrothermal Liquefaction

Depolymerization of Household Plastic Waste via Catalytic Hydrothermal Liquefaction

Impact of Bentonite Clay on In Situ Pyrolysis vs. Hydrothermal Carbonization of Avocado Pit Biomass

Role and Responsibility of Sustainable Chemistry and Engineering in Providing Safe and Sufficient Nitrogen Fertilizer Supply at Turbulent Times

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