Recycling of spent solid CO2 adsorbents via catalytic pyrolysis for the recovery of mesoporous silica and valuable heteroaromatic chemicals

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A technical and environmental comparison of novel silica PEI adsorbent-based and conventional MEA-based CO2 capture technologies in the selected cement plant

The cement industry accounts for almost 7 % of anthropogenic carbon dioxide emissions globally. Therefore, it is imperative to identify innovative solutions to mitigate carbon dioxide emissions from the cement industry.This study aims to evaluate and compare the technical and environmental aspects of integrating two post combustion carbon capture processes (CCS) into a cement plant: the conventional monoethanolamine (MEA)-based CCS process and the novel silica-alkoxylated polyethyleneimine (SPEI)-based CCS process. Three scenarios were considered: (i) a reference cement plant without CCS, (ii) the conventional MEA-based CCS system integrated into a cement plant and (iii) the novel SPEI-based CCS system integrated into a cement plant. The technical evaluation results showed that the regeneration energy requirements for the conventional MEA and novel SPEI based CCS processes were 3.53 GJ/tonne CO2 and 2.36 GJ/tonne CO2, respectively, to achieve a capture rate of 90 %. However, the performance of MEA-based carbon capture processes can be improved by using advanced amine formulations that offer lower regeneration heat requirements at 3.3 GJ/tonne CO2, although this is still higher than the SPEI-based carbon capture processes.The novel SPEI-based CCS process showed superior environmental performance compared to the conventional MEA-based CCS process. The endpoint single score was conducted which showed that the SPEI-based CCS process had a lower impact on human health, ecosystems, and resources (7 %, 9 %, and 26 % lower, respectively) compared to the MEA-based CCS process.<br/

Comparative study on catalytic and non-catalytic pyrolysis of olive mill solid wastes

In this study, catalytic and non-catalytic fast pyrolysis of dried olive husk and olive kernels was carried out. A bubbling fluidised bed reactor was used for the non-catalytic processing of the solid olive wastes. In-situ catalytic upgrading of biomass fast pyrolysis vapours was performed in a fixed bed bench-scale reactor at 500 °C, for catalyst screening purposes. A maximum bio-oil yield of 47.35 wt.% (on dry biomass) was obtained from non-catalytic fast pyrolysis at a reaction temperature of 450 °C, while the bio-oil yield was decreased at 37.14 wt.% when the temperature was increased to 500 °C. In the case of the fixed bed unit tests, the highest liquid (52.66 wt.%) and organics (30.99 wt.%) yield was achieved with the use of the non-catalytic silica sand. Depending on the catalytic material, the liquid yield ranged from 47.03 to 43.96 wt.% the organic yield from 21.15 to 16.34 wt.% on dry biomass. Solid products were increased from 28.23 wt.% for the non-catalytic run to 32.81 wt.% on dry biomass, when MgO (5% Co) was used

GC-MS analysis of alkylpyrazines in the pyrolysis oils of silica-polyethylenimine CO2 sorbents

Solid sorbents based on silica and polyethyleneimine (PEI) are intensively investigated in the field of carbon capture and storage (CCS). Pyrolysis was proposed as a thermal process to recover the pure silica from exhausted sorbents and convert PEI into potentially useful products, such as alkylated pyrazines. A GC-MS method based on internal standardisation with 2-methoxypyrazine was developed and evaluated to determine the concentration of six pyrazines in the pyrolysis oils of exhausted silica-PEI sorbent pyrolysed at 400, 500, 600 and 650°C. The most abundant pyrazines were 2-ethyl and 2,3-dimethyl, occurring at concentrations of 5-28 mg g−1, followed by pyrazine, 2-methyl, 2-ethyl-3-methyl and 2-propylpyrazine. The GC-MS results were compared to those from a HPLC-DAD method using the Welch's test. The 37 % discrepancy of concentrations was attributed to spectral interference in LC-DAD. GC was slightly less precise than HPLC, calibration errors were lower and enabled the identification of highly alkylated pyrazines. Both methods provided comparable values of total pyrazine yields (around 4-7 % by weight)

The decision rule approach to optimization under uncertainty: methodology and applications

Dynamic decision-making under uncertainty has a long and distinguished history in operations research. Due to the curse of dimensionality, solution schemes that naïvely partition or discretize the support of the random problem parameters are limited to small and medium-sized problems, or they require restrictive modeling assumptions (e.g., absence of recourse actions). In the last few decades, several solution techniques have been proposed that aim to alleviate the curse of dimensionality. Amongst these is the decision rule approach, which faithfully models the random process and instead approximates the feasible region of the decision problem. In this paper, we survey the major theoretical findings relating to this approach, and we investigate its potential in two applications areas

GREEK LIGNITE PYROLYSIS

THIS WORK CONCERNS GREEK LIGNITE PYROLYSIS IN A FLUID BED REACTOR AND IN NITROGEN ATMOSPHERE. THE EXPERIMENTAL SYSTEM HAS SOME ADVANTAGES: HIGH HEATING RATES,REAL ISOTHERMAL CONDITIONS AND ON-LINE MEASUREMENTS OF TOTAL GASES AND HYDROCARBONS PRODUCED DURING PYROLYSIS. IN THIS WORK THE INFLUENCE OF FIVE VARIABLES ON THE PYROLYSIS YIELDS WAS STUDIED. THESE VARIABLES ARE: TEMPERATURE, PARTICLE SIZE, TYPE OF COAL, INORGANIC CONSTITUENTS AND VOLATILES RESIDENCE TIME. IT WASCONCLUDED THAT PYROLYSIS TEMPERATURE IS THE MOST IMPORTANT VARIABLE WHICH AFFECTS THE YIELD AND DISTRIBUTION OF PYROLYSIS PRODUCTS. GREEK LIGNITE PRODUCES MAINLY GAS AND SOLID PRODUCTS. THE LIQUID YIELD IS VERY LOW. IN THE PRODUCED GASES THE OXYGEN COMPOUNDS CO2, CO ARE DOMINATED. A VARIETY OF HYDROCARBONS AND HYDROGEN ARE ALSO PRODUCED IN RELATIVELY HIGH QUANTITIES. FOR THE KINETIC STUDIES OF PYROLYSIS PRODUCTS THE ANTHONY AND HOWARD MODEL WAS APPLIED WHICH WAS FOUND SATISFACTORY. THE NON-IDEALITY OF EXPERIMENTAL SYSTEM WAS TAKEN INTO ACCOUNT FOR THE KINETIC STUDIES. FINALLY A GENERAL MODEL WAS DEVELOPED WHICH INCLUDES THESIMULTANEOUS HEAT AND MASS TRANSFER ALONG WITH THE KINETICS OF PYROLYSIS REACTION. USING THE TRANSPORT PHENOMENA MODEL THE EFFECT OF THE VARIOUS RESISTANCES ON THE PYROLYSIS PRODUCTS WAS STUDIED.Η ΤΑΧΕΙΑ ΠΥΡΟΛΥΣΗ ΕΛΛΗΝΙΚΟΥ ΛΙΓΝΙΤΗ ΜΕΛΕΤΗΘΗΚΕ ΣΕ ΑΝΤΙΔΡΑΣΤΗΡΑ ΡΕΥΣΤΟΣΤΕΡΕΑΣ ΚΛΙΝΗΣ ΣΕ ΑΤΜΟΣΦΑΙΡΑ ΑΖΩΤΟΥ. ΤΟ ΠΑΡΩΝ ΠΕΙΡΑΜΑΤΙΚΟ ΣΥΣΤΗΜΑ ΠΡΟΣΦΕΡΕ ΥΨΗΛΟΥΣ ΡΥΘΜΟΥΣ ΘΕΡΜΑΝΣΗΣ, ΚΑΛΕΣ ΙΣΟΘΕΡΜΟΚΡΑΣΙΑΚΕΣ ΣΥΝΘΗΚΕΣ ΚΑΘΩΣ ΚΑΙ ΣΥΝΕΧΗ ΜΕΤΡΗΣΗ ΤΩΝ ΠΡΟΙΟΝΤΩΝ ΠΥΡΟΛΥΣΗΣ. ΠΡΟΣΔΙΟΡΙΣΤΗΚΕ Η ΕΠΙΔΡΑΣΗ ΤΩΝ ΕΞΗΣ ΜΕΤΑΒΛΗΤΩΝ ΣΤΗΝ ΣΥΝΟΛΙΚΗ ΑΠΟΔΟΣΗ ΚΑΙ ΤΗΝ ΚΑΤΑΝΟΜΗ ΤΩΝ ΠΡΟΙΟΝΤΩΝ ΠΥΡΟΛΥΣΗΣ: ΘΕΡΜΟΚΡΑΣΙΑ, ΜΕΓΕΘΟΣ ΣΩΜΑΤΙΔΙΩΝ, ΕΙΔΟΣ ΛΙΓΝΙΤΗ, ΑΝΟΡΓΑΝΑ ΣΥΣΤΑΤΙΚΑ ΚΑΙ ΧΡΟΝΟΣ ΠΑΡΑΜΟΝΗΣ ΠΤΗΤΙΚΩΝ. ΑΠΟ ΤΙΣ ΠΡΟΗΓΟΥΜΕΝΕΣ ΜΕΤΑΒΛΗΤΕΣ Η ΘΕΡΜΟΚΡΑΣΙΑ ΠΥΡΟΛΥΣΗΣ ΕΙΝΑΙ Η ΠΙΟ ΣΗΜΑΝΤΙΚΗ. Η ΑΞΙΟΛΟΓΗΣΗΤΟΥ ΕΛΛΗΝΙΚΟΥ ΛΙΓΝΙΤΗ ΕΔΕΙΞΕ ΟΤΙ ΤΑ ΥΓΡΑ ΠΡΟΙΟΝΤΑ ΠΥΡΟΛΥΣΗΣ ΕΧΟΥΝ ΠΟΛΥ ΜΙΚΡΕΣ ΑΠΟΔΟΣΕΙΣ ΕΝΩ ΤΑ ΑΕΡΙΑ ΚΑΙ ΣΤΕΡΕΑ ΠΡΟΙΟΝΤΑ ΥΨΗΛΕΣ. ΑΠΟ ΤΑ ΑΕΡΙΑ ΠΡΟΙΟΝΤΑ ΚΥΡΙΑΡΧΟΥΝ ΟΙ ΕΝΩΣΕΙΣ CO2, CO ΕΝΩ ΠΑΡΑΓΟΝΤΑΙ ΣΕ ΣΧΕΤΙΚΑ ΥΨΗΛΕΣ ΑΠΟΔΟΣΕΙΣ ΔΙΑΦΟΡΟΙ ΥΔΡΟΓΟΝΑΝΘΡΑΚΕΣ ΚΑΙ ΥΔΡΟΓΟΝΟ. Η ΚΙΝΗΤΙΚΗ ΤΗΣ ΕΚΛΥΣΗΣ ΤΟΥ ΚΑΘΕ ΠΡΟΙΟΝΤΟΣ ΠΥΡΟΛΥΣΗΣ ΠΡΟΣΔΙΟΡΙΣΤΗΚΕ ΜΕ ΒΑΣΗ ΤΟ ΚΙΝΗΤΙΚΟ ΜΟΝΤΕΛΟ ΤΩΝ ANTHONY ΚΑΙ HOWARD ΠΟΥ ΕΡΜΗΝΕΥΣΕΙΚΑΝΟΠΟΙΗΤΙΚΑ ΤΑ ΠΕΙΡΑΜΑΤΙΚΑ ΑΠΟΤΕΛΕΣΜΑΤΑ. ΓΙΑ ΤΗΝ ΚΙΝΗΤΙΚΗ ΜΕΛΕΤΗ ΕΛΗΦΘΗΚΕ ΥΠ'ΟΨΗ Η ΜΗ ΙΔΑΝΙΚΟΤΗΤΑ ΤΟΥ ΠΕΙΡΑΜΑΤΙΚΟΥ ΣΥΣΤΗΜΑΤΟΣ. ΤΕΛΟΣ ΑΝΑΠΤΥΧΘΗΚΑΝ ΜΟΝΤΕΛΑ ΟΠΟΥ ΛΑΜΒΑΝΟΝΤΑΙ ΥΠΟΨΗ ΟΙ ΕΠΙΔΡΑΣΕΙΣ ΤΩΝ ΔΙΑΦΟΡΩΝ ΦΑΙΝΟΜΕΝΩΝ ΜΕΤΑΦΟΡΑΣ ΣΤΗΝ ΠΑΡΑΓΩΓΗ ΤΩΝ ΑΕΡΙΩΝ ΠΡΟΙΟΝΤΩΝ ΠΥΡΟΛΥΣΗΣ . ΑΠΟ ΤΑ ΜΟΝΤΕΛΑ ΑΥΤΑ ΔΙΑΠΙΣΤΩΘΗΚΕ ΠΩΣ ΟΙ ΔΙΑΦΟΡΕΣ ΑΝΤΙΣΤΑΣΕΙΣ ΕΠΗΡΕΑΖΟΥΝ ΤΗΝ ΣΤΙΓΜΙΑΙΑ ΑΠΟΔΟΣΗ ΤΩΝ ΑΕΡΙΩΝ ΠΡΟΙΟΝΤΩΝ

Use of Cost-Adjusted Importance Measures for Aircraft System Maintenance Optimization

The development of an aircraft maintenance planning optimization tool and its application to an aircraft component is presented. Various reliability concepts and approaches have been analyzed, together with objective criteria which can be used to optimize the maintenance planning of an aircraft system, subsystem or component. Wolfram&reg; Mathematica v10.3 9 (Witney, UK) has been used to develop the novel optimization tool, the application of which is expected to yield significant benefits in selecting the most appropriate maintenance intervention based on objective criteria, in estimating the probability of nonscheduled maintenance and in estimating the required number of spare components for both scheduled and nonscheduled maintenance. As such, the results of the application of the tool can be used to assist the risk planning process for future system malfunctions, providing safe projections to facilitate the supply chain of the end user of the system, resulting in higher aircraft fleet operational availability