Samuele Furfari

Fixed-bed pyrolysis of coal under hydrogen pressure at low heating rates☆

Abstract Fixed-bed hydropyrolysis has been investigated by treating 100 g coal up to 900°C and 10 MPa. The devolatilization rate of Beringen coal (32.8 wt% volatile matter) treated on a fixed bed approximates to that obtained by flash hydropyrolysis. However, the oil yield is smaller because of the slower heating of the coal and the rather longer residence time of the primary volatile matter in the reaction space. The product gas is mainly methane. The oil composition depends on the temperature of pyrolysis. The benzene content of the oil rises with temperature. At constant temperature, the influence of hydrogen partial pressure is important between 0–1 MPa. At higher pressure, the yields and compositions vary only slightly with pressure. It has also been shown that from 580°C pyrolysis under hydrogen yields an additional quantity of water, when compared with pyrolysis under inert atmospheres or under atmospheric pressure. This additional water comes from the hydrogenation reactions of the hydroxyl functions of heavy phenols and xylenols. This implies a hydrogen consumption (from 0.2–0.3 wt% of the coal), varying with the pyrolysis temperature.

Hydropyrolysis of a high-sulphur-high-calcite Italian Sulcis coal. 1. Hydropyrolysis yields and catalytic effect of the calcite

Abstract Hydropyrolysis (HyPy) of a high-sulphur (4.3 wt% mf) and high-calcite (7.3 wt% mf) subbituminous coal (Sulcis coal) has been studied in a semi-batch fixed-bed reactor under a pressure of 1 or 3 MPa from 580 to 850 °C. The maximum temperature attained is not necessarily the temperature that the reactor is set but depends on the pressure and nature (reactive or not) of the gas; this phenomenon is due to the heat from the exothermic HyPy reaction. There is a correlation between the amount of heat released during the hydrogenation and the amount of water formed. The maximum conversion obtained is 62.5 wt% maf under H 2 at 3 MPa and 850 °C. The char, oil, water, gas (CH 4 , C 2 H 4 , C 2 H 6 , CO, C0 2 ) yields and the oil analysis are reported. A significant proportion of the C0 2 evolved during the reaction results from the decomposition of the mineral matter rich in carbonates. A proportion of the CO evolved results from the degradation of phenols, a reaction which is catalysed by calcite and/or lime, and as a consequence the oil yield is reduced.

Low-temperature hydropyrolysis of coal under pressure of H2-CH4 mixtures

Abstract Hydropyrolysis of a Beringen bituminous coal (VM, 32.8wt%) has been studied in a fixed bed reactor with different gas flows of H2-CH4 and H2-N2 mixtures. At 580 °C, various hydrogen partial pressures between 0 and 1 MPa were used with a total pressure of 1 and 4 MPa. Oil yield increased significantly with increasing hydrogen partial pressure. However, if the difference between partial and total pressure is too large, the oil yield is affected more by the total than the hydrogen partial pressure. Similar effects are observed for the yields of BTX, PCX and naphthalenes except that for the latter the total pressure does not have a significant effect. In the conditions investigated the methane is chemically inert. Thus it is possible to recycle the gas during coal hydropyrolysis with only a slight decrease of the yields.

Direct post-cracking of volatiles from coal hydropyrolysis: 1. Influence of post-cracking temperature

Abstract Direct post-cracking of volatiles from fixed-bed hydropyrolysis of bituminous coal at 580 °C and 1 MPa hydrogen pressure has been studied between 600 and 900 °C at residence times of 0.1 and 1 s. Results showed that post-cracking promotes the formation of gas, mainly methane, at the expense of oil yield. However, the oil composition was richer in benzene, toluene and xylenes (BTX fraction), in naphthalene and methylnaphthalenes, and poorer in phenol, cresols and xylenols (PCX) content. The optimum temperature for post-cracking under conditions investigated was ≈800 °C, but at this temperature the PCX yield was reduced by 40–60%. The PCX formation rate, from heavier phenols, was lower than the PCX dehydroxylation.

Hydropyrolysis of a high-sulphur-high-calcite Italian Sulcis coal. 2. Importance of the mineral matter on the sulphur behaviour

Abstract The sulphur distribution among the char, oil and gas obtained after hydropyrolysis of a high-sulphur (4.3 wt%) and high-calcite (7.3 wt%) coal has been investigated. The chars were examined by scanning electron microscopy coupled with an energy dispersion analyser and by X-ray diffraction. The proportion of the combustible and non-combustible sulphur in the char has been determined. Hydrogen pressure promotes reaction with sulphur but the sulphur content of the chars increases from 3 to 4.5 wt% when the temperature is increased from 616 to 845 °C. This increase in sulphur is a consequence of the reaction between hydrogen sulphide, produced during hydropyrolysis of coal, with the alkaline-earth mineral matter to produce alkaline-earth sulphide. The SEM and X-ray diffraction images show that in the char formed at 780 °C the sulphur, calcium and magnesium are localized in the same compounds. This is not the case when hydropyrolysis is performed at lower temperature. Combustion of the chars produces only 2 MJ −1 compared to 2.2 g S0 2 MJ −1 for untreated coal. X-ray diffraction has shown that the sulphur in the char is oxidized and fixed in the ashes mainly as CaS0 4 and also some as MgS0 4 . Although sulphur remains partly in the chars after hydropyrolysis, 75% of it is non-combustible. The hydropyrolysis of a high-sulphur coal containing calcite, produces a char which may be used as a clean fuel.

Hydropyrolysis of a high-sulphur, high-calcite Italian Sulcis coal: 3. Pyrite behaviour

Abstract The chars obtained from hydtopytolysis of Sulcis coal were examined by scanning electron microscopy coupled with an energy dispersion analyser. Under 3 MPa of He at 540 °C, pyrite is transformed into FeS1.5. Under H2 pressure, pyrite reduction depends on the temperature. At 780 °C, pyrite is completely reduced to iron. The complete reduction is made possible because the H2S formed reacts with the caleite of this coal and thus does not limit the reducing reaction.

Direct post-cracking of volatiles from coal hydropyrolysis: 2. Influence of pressure

Abstract Direct post-cracking of volatile material produced by hydropyrolysis of bituminous coal at 580 °C under hydrogen pressure 1–5 MPa has been investigated at 700 °C under constant hydrogen pressure with 0.1 and 1 s residence times. Results show that pressure promotes the formation of benzene, toluene and xylenes (BTX) and naphthalenes during post-cracking, while phenol, cresols and xylenols (PCX) are not affected. The transformation of heavy Ohenols into PCX is not influenced by the hydrogen pressure. During post-cracking the BTX yield can be more than doyble that reached in simple hydropyrolysis. Post-cracking applied to high oil yield hydropyrolysis processes will be a valuable BTX source.

Thermogravimetric study of the devolatilization of hydropyrolysis chars

Abstract The devolatilization of hydropyrolysis (HyPy) chars formed at 485–850 °C under 3 MPa and chars formed at 580 °C under 0–5 MPa of H 2 and 3 MPa He is investigated in a thermobalance coupled to two gas chromatographs. The H 2 , CH 4 and CO 2 released are analysed every 4 min and all are analysed at the end of the experiment. The amount of residual volatile matter in the chars decreases rectilinearly with the HyPy temperature, whereas their decrease is asymptotic with the HyPy pressure. The char formed under He contains 45% more residual volatile matter than that formed in the same conditions under H 2 . The HyPy temperature must be limited if the char is to be burned in a boiler. The CH 4 formation is strongly dependant of the HyPy temperature.

Energy efficiency of engines and appliances for transport on land, water, and in air

The transport sector is fundamental for the economy but also for personal life. With a growing population and the globalization process, it is not surprising that the demand of transport is set to grow in the near future and certainly until 2050. This paper focuses on the huge potential of progress in the sector of technology for transport. As the principal sector for transport will remain on roads, the paper emphasizes the progress in the automotive sector. Since car manufacturers are investing massively into research and technology development to offer ever more efficient cars—not only energy efficient but also efficient in terms of safety and comfort—the car of tomorrow will be very different from the present one. The increasing role of electronics in cars will synergistically cooperate with that of so-called smart cities. The potential development of methane in the transport sector, mainly used for heavy transportation is discussed.