Dechlorination of polyvinyl chloride by hydrothermal treatment with cupric ion

Hydrothermal treatment (HTT) is able to remove chlorine effectively from polyvinyl chloride (PVC), however, the reaction temperature is critical in practical application. Less energy-intensive hydrothermal dechlorination condition with cupric ion (Cu2+) has been proposed in this study. In particular, Cu2+ was applied in HTT of PVC at temperature ranging from 200 °C to 240 °C. It has been found that the introduction of Cu2+ distinctly accelerated PVC decomposition and dechlorination at 220 °C. When Cu2+ concentration was increased from 0.01 mol/L to 0.20 mol/L, the dechlorination efficiency was significantly improved from 15.46 %–67.89 %. Dramatic dechlorination occurred as residence time was longer than 15 min during HTT. Besides, both elimination and substitution dominated the HTT dechlorinaton. The facilitated dechlorination after the addition of Cu2+ was mainly due to the enhanced dispersion and formation of micropores in hydrochar. On the whole, HTT could be a promising pretreatment technology for copper-containing PVC in electronic wastes to prepared chlorine free hydrochar for combustion or pyrolysis applications, the optimal HTT condition would be 220 °C, 60 min with 0.1 mol/L Cu2+.acceptedVersionPeer reviewe

Quantitative Analysis of Pore Structure and Its Impact on Methane Adsorption Capacity of Coal

Better understanding of the storage and transportation characteristics of methane in coal seams is important to further develop and utilize the methane resources in the coalbed. This study is devoted to investigating the relationship between methane adsorption performance and pore structure by analyzing twelve coal samples derived from the typical methane-rich coalbeds in China. To eliminate the influence of inorganic components such as ash in different coal samples, a specific fixed-bed reactor with internals was employed for the coal treatment. Based on N-2/CO(2)adsorption analysis at low-pressure condition, the pores in coal were classified into three types in this study: ultra-micropore (pore width ultra-micropore surface area (0.8976) > fractal dimension D-1(0.8862) > N-2-BET surface area (0.7915) > micropore volume (0.5035) > micropore surface area (0.5006). This study shows the influence of parameters of pore structure on methane adsorption of coal and clarifies the order importance of these parameters by the GRA method

Energy Fuels

Using internals in kilogram-laboratory fixed bed pyrolysis of coal has been newly reported to greatly upgrade the pyrolysis performance in terms of the yield and quality of the produced tar and pyrolysis gas. This work is devoted to further verifying such a finding through pyrolysis tests in enlarged fixed bed reactors with and without internals at obviously increased coal treatment capacities of about 100 kg of coal per test. The reactors were electrically heated, and the tests were via batchwise operation, while Yilan sub-bituminous coal was used. Comparing the results from reactors without and with the particularly designed internals demonstrated that the use of internals increased the heating to the coal bed by about 20%, while the tar yield was 87.0% of the Gray-King (G-K) tar yield, which was obviously higher than 46.9% of the G-K tar yield from the reactor without internals. In the tar from the internal-enhanced reactor, the content of light tar (boiling point below 360 degrees C) was about 71 wt %. Raising the furnace temperature from 900 to 1100 degrees C increased the tar yield from 80.5% to 90.3% of the Gray-King tar yield for the reactor with internals. Parametric studies were performed for coal particle size, heating furnace temperature, and coal moisture content.Using internals in kilogram-laboratory fixed bed pyrolysis of coal has been newly reported to greatly upgrade the pyrolysis performance in terms of the yield and quality of the produced tar and pyrolysis gas. This work is devoted to further verifying such a finding through pyrolysis tests in enlarged fixed bed reactors with and without internals at obviously increased coal treatment capacities of about 100 kg of coal per test. The reactors were electrically heated, and the tests were via batchwise operation, while Yilan sub-bituminous coal was used. Comparing the results from reactors without and with the particularly designed internals demonstrated that the use of internals increased the heating to the coal bed by about 20%, while the tar yield was 87.0% of the Gray-King (G-K) tar yield, which was obviously higher than 46.9% of the G-K tar yield from the reactor without internals. In the tar from the internal-enhanced reactor, the content of light tar (boiling point below 360 degrees C) was about 71 wt %. Raising the furnace temperature from 900 to 1100 degrees C increased the tar yield from 80.5% to 90.3% of the Gray-King tar yield for the reactor with internals. Parametric studies were performed for coal particle size, heating furnace temperature, and coal moisture content

Effects of Metallic Heating Plates on Coal Pyrolysis Behavior in a Fixed-Bed Reactor Enhanced with Internals

A newly configured fixed-bed reactor with internals has been proposed to enhance the coal pyrolysis performance. In this study, the effects of metallic plates on coal pyrolysis behavior were investigated in this reactor. The results show that the increased quantity of the metallic plates enhanced the heat transfer and shortened the residence time of volatiles within the coal particles. In addition, the pressure drop results suggest that the increased quantity of plates caused short circuiting of gas and raised the particle interstices, which reduced the gas diffusion resistance of pyrolysis products. Therefore, more gaseous pyrolysis products flowed into central low-temperature coal bed and escaped from the gas collection pipe, suppressing the secondary reaction of pyrolysis products and increasing the tar yield and quality. At a furnace temperature of 900 degrees C, the increase in metallic plates from 0 to 8 raised the tar yield and light tar fraction from 5.20 and 69.5 wt % to 7.86 and 77.0 wt %, respectively. Meanwhile, the &lt;= C-14 hydrocarbons were elevated from 42.11 to 50.44 wt %, but the &gt;= C-20 hydrocarbons were lowered from 29.95 to 19.74 wt %. However, an excessive increase in plates raised the heating rate of coal, cracking more pyrolysis products and decreasing the tar yield and quality.</p

Altered Resting-State Brain Activity and Connectivity in Depressed Parkinson's Disease.

Depressive symptoms are common in Parkinson's disease (PD), but the neurophysiological mechanisms of depression in PD are poorly understood. The current study attempted to examine disrupted spontaneous local brain activities and functional connectivities that underlie the depression in PD. We recruited a total of 20 depressed PD patients (DPD), 40 non-depressed PD patients (NDPD) and 43 matched healthy controls (HC). All the subjects underwent neuropsychological tests and resting-state fMRI scanning. The between-group differences in the amplitude of low frequency fluctuations (ALFF) of BOLD signals were examined using post-hoc tests after the analysis of covariance. Compared with the NDPD and HC, the DPD group showed significantly increased ALFF in the left median cingulated cortex (MCC). The functional connectivity (FC) between left MCC and all the other voxels in the brain were then calculated. Compared with the HC and NDPD group, the DPD patients showed stronger FC between the left MCC and some of the major nodes of the default mode network (DMN), including the post cingulated cortex/precuneus, medial prefrontal cortex, inferior frontal gyrus, and cerebellum. Correlation analysis revealed that both the ALFF values in the left MCC and the FC between the left MCC and the nodes of DMN were significantly correlated with the Hamilton Depression Rating Scale score. Moreover, higher local activities in the left MCC were associated with increased functional connections between the MCC and the nodes of DMN in PD. These abnormal activities and connectivities of the limbic-cortical circuit may indicate impaired high-order cortical control or uncontrol of negative mood in DPD, which suggested a possible neural mechanism of the depression in PD

Effect of the Moisture Content in Coal on the Pyrolysis Behavior in an Indirectly Heated Fixed-Bed Reactor with Internals

The fixed-bed reactor with internals has been proposed to enhance the pyrolysis performance for coal. In this study, the pyrolysis behavior of different coal moisture contents and the reaction mechanism were investigated in an indirectly heated fixed-bed reactor with internals. The results showed that, at a furnace temperature of 900 degrees C, the increased coal moisture content went from 0.41 to 11.68 wt % and significantly modified the temperature fields, thereby prolonging the pyrolysis time to reach 500 degrees C and then enhancing the condensation and trapping of the coal at the bed center. Therefore, the tar yield and light tar content were raised from 9.21 and 63.7 wt % to 10.74 and 64.5 wt %, respectively. However, when the coal moisture content exceeded 16.77 wt %, the tar yield and light tar content decreased to 8.55 and 62.0 wt %, respectively. In addition, the higher heating value (HHV) of char with internals was dramatically higher than that without internals, and the char HHV in the reactor with internals rose primarily and then decreased with the increase in the coal moisture; meanwhile, its fixed carbon content of char showed an increase, followed by a decline. In contrast, the pyrolysis products varied slightly in the reactor without internals.</p

Characterization of coal pyrolysis in indirectly heated fixed bed based on field effects

This study is devoted to characterizing the coal pyrolysis performance based on field effects in five fixed bed reactors with different radiuses. The results showed that the increased reactor radius raised the coal bed thickness, thereby modifying the temperatures and extending the reaction time to reach 500 degrees C. At a furnace temperature of 900 degrees C, the increased coal bed thickness from 20 mm to 100 mm decreased the tar yield from 7.24 wt% to 5.62 wt%, while it raised the light tar content from 76.4 wt% to 83.0 wt% in the reactor with internals (reactor B). In contrast, in the reactor without internals (reactor A), the tar yield varied marginally and remained at 4.73 wt% but the light tar content increased from 69.5 wt% to 74.7 wt%. The increased coal bed thickness resulted in an increase in the tar quality but a decrease in the gas HHV (higher heating value) for both reactors. However, with the increase of coal bed thickness, reactor B always provides a higher yield and quality of tar and gas but lower pyrolysis water yield than reactor A, indicating that the internals suppressed the secondary reaction of pyrolysis products and the increase in coal bed thickness did not weaken this advantage of internals. The char HHV located in the center of the reactor with internals was higher than that of the reactor without internals; this was postulated that the pyrolysis products escaped from the central low-temperature coal bed, which enhanced carbon deposition. As expected, EDS results proved the postulation and showed that the char in the center of the reactor B had more carbon species. In addition, the color changes of quartz sand in the before and after tests first verified the flow field of pyrolysis products in phenomenology. (C) 2017 Elsevier Ltd. All rights reserved.</p

Coal pyrolysis and its mechanism in indirectly heated fixed-bed with metallic heating plate enhancement

A metallic plate has been devised to enhance the heat transfer; this in turn increases the yield and quality of coal tar (Zhang et al., 2013). This work is devoted to investigating the pyrolysis of Yilan subbituminous coal and developing a working mechanism for an indirectly heated fixed bed reactor with different number of metallic plates. Increasing the number of metallic heating plates enhanced the heat transfer from the high-temperature reactor wall to the low-temperature central coal layer and thereby shortened the reaction time. Meanwhile, the yields of tar and light fraction were increased then decreased. The results of the pressure drop experiment demonstrated that the metallic plates weakened dense stacks of coal particles and raised the particle interstices, and therefore lowered the gas diffusion resistance. It verified that many gaseous pyrolysis products escaped from the central low-temperature coal layer, indicating the suppressed secondary reactions to the primary products. When the number of plates was 8, the correspondingly added high-temperature surface was 113%; it achieved the optimal matching between the secondary reactions of pyrolysis products and the fields of the temperature as well as the gas flow inside the reactor, and it also had the highest tar yield (6.60 wt.% dry basis) and the maximum content of light tar (below the boiling points of 360 degrees C) of 76.4 wt.% and C4-C9 components of 43.52 wt.%. The BET results showed that the char had the biggest surface area and volume for this case with 8 plates. Consequently, adding suitable metallic plates into the indirectly heated fixed bed reactor obviously enhances the heat transfer and also achieves higher yield and quality of tar. (C) 2016 Published by Elsevier Ltd.</p