Academia.eduAcademia.edu

Figure 4 – uploaded by Ubong Etim

See full PDFdownloadDownload figure
Figure 3. (a) N, adsorption—desorption isotherms and (b) pore size distribution of fresh Ni/ZnO—AI,O, adsorbents.

Figure 3 (a) N, adsorption—desorption isotherms and (b) pore size distribution of fresh Ni/ZnO—AI,O, adsorbents.

Related Figures (13)

"State Key Laboratory of Heavy Oil Processing, PetroChina Key Laboratory of Catalysis, China University of Petroleum, Qingdao, 266555, China *Petrochina Petrochemical Research Institute, Beijing 102206, China ‘Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Science, Qingdao 266101, China
"State Key Laboratory of Heavy Oil Processing, PetroChina Key Laboratory of Catalysis, China University of Petroleum, Qingdao, 266555, China *Petrochina Petrochemical Research Institute, Beijing 102206, China ‘Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Science, Qingdao 266101, China
Figure 2. Sulfur capacities of adsorbents with a fuel processing amount of 30 mL under investigated conditions. ZnO—Al,O;(28 °C) prepared at 28 °C showed the highest activity for thiophene desulfurization among the selected six samples. After dealing with 15 mL of fuel, sample Ni/ZnO— AL,O;(28 °C) achieved a thiophene conversion of 98%. Upon dealing with more model fuel, the thiophene conversion gradually decreased to 91% after processing 30 mL of model fuel with a corresponding sulfur capacity of 79 mg of S/g (see Figure 2), which is 3-fold higher than those of adsorbents
Figure 2. Sulfur capacities of adsorbents with a fuel processing amount of 30 mL under investigated conditions. ZnO—Al,O;(28 °C) prepared at 28 °C showed the highest activity for thiophene desulfurization among the selected six samples. After dealing with 15 mL of fuel, sample Ni/ZnO— AL,O;(28 °C) achieved a thiophene conversion of 98%. Upon dealing with more model fuel, the thiophene conversion gradually decreased to 91% after processing 30 mL of model fuel with a corresponding sulfur capacity of 79 mg of S/g (see Figure 2), which is 3-fold higher than those of adsorbents
Figure 1. Reactive adsorption desulfurization performance of adsorbents prepared at different crystallization temperatures.
Figure 1. Reactive adsorption desulfurization performance of adsorbents prepared at different crystallization temperatures.
Table 1. Textural Properties of Fresh and Spent Ni/ZnO—AL,O; Adsorbents Prepared at Different Temperatures remains intact during the RADS process as verified in Figure Sb. Only free or weakly interacted ZnO is reactive with H,S and can be converted to ZnS via a nucleation control sulfidation process during the RADS process,.71974~77 Hence, it is reasonable to note that the intensities of ZnS reflections show a reverse trend compared with those of ZnAl,O, reflections. As a consequence, sample Ni/ZnO—Al,03(28 °C) exhibits ZnS peaks with the highest intensities among all samples, implying the highest conversion of ZnO to ZnS.** The above XRD findings suggest that the adsorbent prepared at a low crystallization temperature may contain a high concen- tration of highly dispersed ZnO phase weakly interacted with Al,O3, which gives rise to its high RADS reactivity and large sulfur capacity.
Table 1. Textural Properties of Fresh and Spent Ni/ZnO—AL,O; Adsorbents Prepared at Different Temperatures remains intact during the RADS process as verified in Figure Sb. Only free or weakly interacted ZnO is reactive with H,S and can be converted to ZnS via a nucleation control sulfidation process during the RADS process,.71974~77 Hence, it is reasonable to note that the intensities of ZnS reflections show a reverse trend compared with those of ZnAl,O, reflections. As a consequence, sample Ni/ZnO—Al,03(28 °C) exhibits ZnS peaks with the highest intensities among all samples, implying the highest conversion of ZnO to ZnS.** The above XRD findings suggest that the adsorbent prepared at a low crystallization temperature may contain a high concen- tration of highly dispersed ZnO phase weakly interacted with Al,O3, which gives rise to its high RADS reactivity and large sulfur capacity.
Figure 4. (a) N, adsorption—desorption isotherms and (b) pore size distribution of spent Ni/ZnO—AI,O; adsorbents.
Figure 4. (a) N, adsorption—desorption isotherms and (b) pore size distribution of spent Ni/ZnO—AI,O; adsorbents.
Figure 5. XRD patterns of Ni/ZnO—AL O, adsorbents (a) before and (b) after RADS tests.
Figure 5. XRD patterns of Ni/ZnO—AL O, adsorbents (a) before and (b) after RADS tests.
Figure 6. UV-vis DRS spectra of Ni/ZnO-—AI,O, adsorbents prepared at 28, 60, and 100 °C. 3.4. UV—Visible DRS Analysis. In order to further understand the chemical states of ZnO in the mixed oxides, the Ni/ZnO—AI,O, adsorbents synthesized at 28, 60, and 100 °C were characterized using UV—vis DRS spectroscopy.”””° As shown in Figure 6, a broad absorbance peak at ca. 300 nm is
Figure 6. UV-vis DRS spectra of Ni/ZnO-—AI,O, adsorbents prepared at 28, 60, and 100 °C. 3.4. UV—Visible DRS Analysis. In order to further understand the chemical states of ZnO in the mixed oxides, the Ni/ZnO—AI,O, adsorbents synthesized at 28, 60, and 100 °C were characterized using UV—vis DRS spectroscopy.”””° As shown in Figure 6, a broad absorbance peak at ca. 300 nm is
Figure 7. Raman spectra of Ni/ZnO—AI,O; adsorbents. 3.5. Raman Analysis. Raman spectra of Ni/ZnO—Al,O,; adsorbents prepared at 28, 60, and 100 °C are shown in Figure 7. The Raman-active mode (E,) at around 99 cm‘ is attributed
Figure 7. Raman spectra of Ni/ZnO—AI,O; adsorbents. 3.5. Raman Analysis. Raman spectra of Ni/ZnO—Al,O,; adsorbents prepared at 28, 60, and 100 °C are shown in Figure 7. The Raman-active mode (E,) at around 99 cm‘ is attributed
Figure 8. H,-TPR profiles (a) and deconvoluted TPR profiles (b) of Ni/ZnO—Al,O, samples synthesized at different crystallization temperatures and sample ZnO—Al,O3.
Figure 8. H,-TPR profiles (a) and deconvoluted TPR profiles (b) of Ni/ZnO—Al,O, samples synthesized at different crystallization temperatures and sample ZnO—Al,O3.
Figure 9. SEM image (a), TEM image (b), and elemental distribution mapping of oxygen (c), aluminum (d), nickel (e), and zinc (f) on Ni/ZnO- Al,O;(28 °C) before RADS activity. Figure 10. HRTEM image of Ni/ZnO—Al,O;(28 °C) after RADS activity exposing ZnS (red circles) and ZnAl,O, phases (green circles).
Figure 9. SEM image (a), TEM image (b), and elemental distribution mapping of oxygen (c), aluminum (d), nickel (e), and zinc (f) on Ni/ZnO- Al,O;(28 °C) before RADS activity. Figure 10. HRTEM image of Ni/ZnO—Al,O;(28 °C) after RADS activity exposing ZnS (red circles) and ZnAl,O, phases (green circles).
Figure 11. Regeneration performance of Ni/ZnO—AI,0,(28 °C) adsorbent.
Figure 11. Regeneration performance of Ni/ZnO—AI,0,(28 °C) adsorbent.
may act as shields to segregate the ZnO crystals to achieve a high dispersion of ZnO and prevent them from sintering during the high temperature regeneration process. Beside, some Zn™* ions interact strongly with aluminate spinels in the ZnAl,O, crystals,” which may protect the remaining chemically free ZnO from further interaction with the aluminate spinels to form inactive ZnAl,O,."° 2. The adsorbent synthesized at a lower crystallization temperature possesses better pore architecture in terms of larger pore size and higher pore volume, which favors the diffusion of reactants and product in the pore network. Furthermore, the pore shrinkage/blockage due to the frame- work volume expansion during the sulfidation of ZnO to ZnS could be alleviated.
may act as shields to segregate the ZnO crystals to achieve a high dispersion of ZnO and prevent them from sintering during the high temperature regeneration process. Beside, some Zn™* ions interact strongly with aluminate spinels in the ZnAl,O, crystals,” which may protect the remaining chemically free ZnO from further interaction with the aluminate spinels to form inactive ZnAl,O,."° 2. The adsorbent synthesized at a lower crystallization temperature possesses better pore architecture in terms of larger pore size and higher pore volume, which favors the diffusion of reactants and product in the pore network. Furthermore, the pore shrinkage/blockage due to the frame- work volume expansion during the sulfidation of ZnO to ZnS could be alleviated.
Related topics:
Heterogeneous CatalysisPetroleum refining and petrochemicals
580 California St., Suite 400
San Francisco, CA, 94104
© 2025 Academia. All rights reserved