scholarly journals Turning Carbon Dioxide and Ethane into Ethanol by Solar-Driven Heterogeneous Photocatalysis over RuO2- and NiO-co-Doped SrTiO3

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 461
Author(s):  
Larissa O. Paulista ◽  
Josep Albero ◽  
Ramiro J. E. Martins ◽  
Rui A. R. Boaventura ◽  
Vítor J. P. Vilar ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Maximum Yield ◽  
Ruthenium Oxide ◽  
Photogenerated Electron ◽  
Band Gap Energy ◽  
Heterogeneous Photocatalysis ◽  
Solar Irradiation ◽  
Batch Mode ◽  
Molar Ratios ◽  
Co Doped

The current work focused on the sunlight-driven thermo-photocatalytic reduction of carbon dioxide (CO2), the primary greenhouse gas, by ethane (C2H6), the second most abundant element in shale gas, aiming at the generation of ethanol (EtOH), a renewable fuel. To promote this process, a hybrid catalyst was prepared and properly characterized, comprising of strontium titanate (SrTiO3) co-doped with ruthenium oxide (RuO2) and nickel oxide (NiO). The photocatalytic activity towards EtOH production was assessed in batch-mode and at gas-phase, under the influence of different conditions: (i) dopant loading; (ii) temperature; (iii) optical radiation wavelength; (vi) consecutive uses; and (v) electron scavenger addition. From the results here obtained, it was found that: (i) the functionalization of the SrTiO3 with RuO2 and NiO allows the visible light harvest and narrows the band gap energy (ca. 14–20%); (ii) the selectivity towards EtOH depends on the presence of Ni and irradiation; (iii) the catalyst photoresponse is mainly due to the visible photons; (iv) the photocatalyst loses > 50% efficiency right after the 2nd use; (v) the reaction mechanism is based on the photogenerated electron-hole pair charge separation; and (vi) a maximum yield of 64 μmol EtOH gcat−1 was obtained after 45-min (85 μmol EtOH gcat−1 h−1) of simulated solar irradiation (1000 W m−2) at 200 °C, using 0.4 g L−1 of SrTiO3:RuO2:NiO (0.8 wt.% Ru) with [CO2]:[C2H6] and [Ru]:[Ni] molar ratios of 1:3 and 1:1, respectively. Notwithstanding, despite its exploratory nature, this study offers an alternative route to solar fuels’ synthesis from the underutilized C2H6 and CO2.

WO3/Nb2O5 Nanoparticles-Decorated Hierarchical Porous ZnO Microspheres for Enhanced Photocatalytic Degradation of Palm Oil Mill Effluent and Simultaneous Production of Biogas

2019 ◽  
Vol 821 ◽  
pp. 379-385 ◽  
Author(s):  
Jin Chung Sin ◽  
Ying Hui Chin ◽  
Sze Mun Lam
Keyword(s):  
Palm Oil ◽  
Separation Efficiency ◽  
Photocatalytic Property ◽  
Photogenerated Electron ◽  
Band Gap Energy ◽  
Heterogeneous Photocatalysis ◽  
Palm Oil Mill Effluent ◽  
Hierarchical Porous ◽  
Palm Oil Mill ◽  
Photocatalytic Reactions

Conventionally, palm oil mill effluent (POME) was treated using open ponding system, which nevertheless long retention times and large treatment areas were required. In this report, heterogeneous photocatalysis was used to degrade the POME and simultaneously assessed the biogas formation. Characterization of the chemically prepared hierarchical porous ZnO microspheres showed that wurtzite was the predominant crystalline phase with a band gap energy of 3.22 eV. Moreover, the as-prepared ZnO were assembled by large numbers of interleaving nanosheets and formed an open porous structure. Under UV irradiation, the as-prepared ZnO demonstrated photocatalytic property on POME degradation. The WO3 and Nb2O5 decorated ZnO photocatalysts (WO3/ZnO and Nb2O5/ZnO) with improved photocatalytic performances were also prepared using a simple and rapid way. Significantly, in the presence of WO3/ZnO and Nb2O5/ZnO composites, the degradation of POME achieved 68.3% and 91.7%, respectively after 240 min irradiation. Interestingly, the assessment of the biogas formation showed that the photocatalytic reactions over Nb2O5/ZnO and WO3/ZnO composites generated higher amount of biogas products (CH4 + CO2) compared to that of ZnO. The photocatalytic enhancement was attributed to the high separation efficiency of photogenerated electron–hole pairs based on the formation of heterojunction structures between the WO3/Nb2O5 and ZnO. The observed findings also revealed that the photocatalytic technology using hierarchical WO3/ZnO and Nb2O5/ZnO composites had the potential to efficiently treat wastewater.

scholarly journals Synthesis and Optical Properties of B-Mg co-Doped ZnO Nanoparticles

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 882
Author(s):  
Yuechan Li ◽  
Yongli Li ◽  
An Xie
Keyword(s):  
Optical Properties ◽  
Zno Nanoparticles ◽  
Great Influence ◽  
Structure Study ◽  
Band Gap Energy ◽  
One Pot ◽  
Gap Energy ◽  
Doping Impurity ◽  
Shrinkage Effect ◽  
Co Doped

Doping impurity into ZnO is an effective and powerful technique to tailor structures and enhance its optical properties. In this work, Zn1−xMgxO and Zn1−x−yMgxByO nanoparticles (x = 0, 0.1, 0.2, 0.3, 0.4; y = 0, 0.02, 0.04) were synthesized via one-pot method. It shows that the Mg and B dopants has great influence on crystallinity and surface morphology of ZnO nanoparticles, without changing the wurtzite structure of ZnO. The band structure study indicates that the competition of Conductive Band (CB) shift, Burstein–Moss (B-M) shift and Shrinkage effect will cause the band gap energy change in ZnO.

scholarly journals Factors influencing the adsorption and photocatalysis of direct red 80 in the presence of a TiO2: Equilibrium and kinetics modeling

2021 ◽  
pp. 174751982198996
Author(s):  
Moussa Abbas
Keyword(s):  
Elimination Rate ◽  
Threshold Value ◽  
Heterogeneous Photocatalysis ◽  
Order Kinetic ◽  
Batch Mode ◽  
Adsorption Capacities ◽  
Initial Ph ◽  
Equilibrium And Kinetics ◽  
Order Kinetic Model ◽  
Charge Point

Among the different photocatalysts, TiO2 ( Eg = 3.1 eV, zero charge point (pHpzc = 6.3), and surface = 55 m2/g) is currently the most efficient and the most studied semiconductor due to its strong photocatalytic activity, non-toxicity, and chemical stability. The elimination of DR-80 on TiO2 is studied by adsorption in batch mode and by application of heterogeneous photocatalysis onto TiO2 under UV irradiation. The effects of contact time (0–60 min), initial pH (3–11), dose of the adsorbent (0.5–3 g L−1), and DR-80 concentration (40–60 mg L−1) on the adsorption of DR-80 by TiO2 are studied for optimization of these parameters. The kinetic parameters, rate constants, and equilibrium adsorption capacities are calculated and discussed for each applied theoretical model. The adsorption of DR-80 is well described by the pseudo-first-order kinetic model. The fitting of the adsorption isotherms shows that the models of Langmuir and Temkin offering a better fit and an adsorption 64.102 mg/g at 25 °C of DR-80 are eliminated. The results showed that the photocatalytic efficiency strongly depends on the pH while the initial rate of photodegradation is proportional to the catalyst dose, and becomes almost constant above a threshold value. It was found that the photodegradation is favored at low DR-80 concentrations in accordance with the Langmuir–Hinshelwood model with the constants Kad = 6.5274 L/mg and KL–H = 0.17818 mg L−1 min. However, the adsorption is improved for high DR-80 concentrations. It is found that the degradation depends on both the temperature and the pH with a high elimination rate at high temperature. The photocatalyst TiO2 has a better activity for the degradation of DR-80, compared to some commercial catalysts that have been described in the literature.

Nitrogen and boron co‐doped carbon spheres for carbon dioxide electroreduction

ChemNanoMat ◽  
2021 ◽  
Author(s):  
Chunfeng Cheng ◽  
Jiaqi Shao ◽  
Pengfei Wei ◽  
Yanpeng Song ◽  
Hefei Li ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Spheres ◽  
Co Doped ◽  
Carbon Dioxide Electroreduction

scholarly journals PRODUCTION OF EXTRACTS FROM VEGETABLE RAW MATERIALS BY CARBON DIOXIDE

2020 ◽  
Vol 14 (1) ◽  
Author(s):  
K. Gafurov ◽  
B. Muhammadiev ◽  
Sh. Mirzaeva ◽  
F. Kuldosheva
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Co2 ◽  
Raw Materials ◽  
Maximum Yield ◽  
Volumetric Flow Rate ◽  
Extraction Process ◽  
Raw Material ◽  
Critical Conditions ◽  
Plant Materials ◽  
Laboratory Setup

The unique properties of supercritical carbon dioxide as a solvent are widely used for extraction. In supercritical media, the dissolution of molecules of various chemical nature is possible. The purpose of this investigation was to study the extraction process and obtain extracts from valuable regional plant materials by applying CO2 extraction under pre- and supercritical conditions. The objects of research were: ground seeds of melon, pumpkin and licorice roots, as well as mint leaves, mulberry and jida flowers. For extraction, a laboratory setup was used that allows extraction when the CO2 is supplied by a high-pressure plunger pump in the sub- and supercritical state using a heat pump. The pressure range is 3-15 MPa, temperatures 295–330 K, and the volumetric flow rate above the critical CO2 is 800–900 g. Experiments with ground seeds of melon and pumpkin showed that as a result of 4 sequentially performed extraction cycles on a single load with supercritical CO2 parameters ( 315–330 K; 3–7.5 MPa) the decrease in the mass of melon seeds was 90 g (pumpkins 80 g). During the total extraction time (2.5 hours), 20 kg of CO2 were pumped through the reactor (25 l at 290 K and 6.8 MPa), while the average oil content in the extract was 4 g per 1 kg of CO2 (3.0 g per 1 l of SС-CO2) In experiments with jida flowers, the maximum amount of solid extractable substance (2% by weight of the raw material) was obtained at a temperature in the extractor of 308 K and a pressure of 7.5 MPa. Upon extraction under critical conditions in collection 2, the liquid phase was absent; only a yellow-green paste was released in it. According to the results of experiments with mint leaves, the maximum yield of a greenish liquid was observed at T = 315 K and P = 4 MPa., Mulberry - at T = 306 K and P = 6.0 MPa. The results of the extraction of oils and extracts from ground seeds of melon, pumpkin and licorice roots, as well as mint leaves, mulberries and jida flowers confirm that the maximum yield of the extracted substance is achieved with supercritical CO2 parameters in the extractor (310 K, 7.5 MPa). When liquid CO2 is extracted (300 K and 6-8 MPa), up to 2% of a yellow substance is extracted, which does not differ in appearance from a supercritical extract.

Up-Conversion Luminescence Properties of Nd3+/Yb3+ Doped Lutetium-Based Oxyfluoride Glass Ceramic

2021 ◽  
Vol 20 (02) ◽  
pp. 2150014
Author(s):  
Yuan Ou ◽  
Xuefei Yan ◽  
Yong Lv ◽  
Chunhui Niu
Keyword(s):  
Oscillator Strength ◽  
Glass Ceramic ◽  
Ceramic Sample ◽  
Glass Sample ◽  
Transition Probability ◽  
Branching Ratio ◽  
Photon Absorption ◽  
Glass Ceramic Sample ◽  
Molar Ratios ◽  
Co Doped

Nd[Formula: see text]/Yb[Formula: see text] co-doped lutetium-based glass sample and glass ceramic sample were prepared with the molar ratios of 52SiO2-8Na2CO3-16Al2O3-33NaF-3LuF3-0.15Yb2O3-0.03Nd2O3 by the high temperature melting method in 1400∘C. Under the excitation of 980[Formula: see text]nm diode laser, up-conversion luminescence spectrum of glass sample and glass ceramic sample was measured and three stronger up-conversion luminescence peaks at the wavelength of 552[Formula: see text]nm, 656[Formula: see text]nm and 668[Formula: see text]nm were observed, and up-conversion luminescence strengths of glass ceramic sample are higher than those of glass sample. The two-photon absorption of three emission peaks was determined by the fitting curve graph of up-conversion emission power and LD wording current. Absorption spectrum of glass ceramic sample was obtained and spectral strength parameters were computed as [Formula: see text][Formula: see text]cm2, [Formula: see text][Formula: see text]cm2, [Formula: see text][Formula: see text]cm2 by adopting Judd–Ofelt theory, and the root mean square deviation between the theoretical oscillator strength and the experimental oscillator strength were calculated as [Formula: see text]. Transition probability, branching ratio of 4F[Formula: see text] to its lower level and lifetime of 4F[Formula: see text] level of Nd[Formula: see text] ions were calculated, and the results indicate that the prepared Nd[Formula: see text]/Yb[Formula: see text] co-doped glass ceramic sample is a kind of good up-conversion material.

Chlorine‐Promoted Nitrogen and Sulfur Co‐Doped Biocarbon Catalyst for Electrochemical Carbon Dioxide Reduction

2020 ◽  
Vol 7 (1) ◽  
pp. 320-327 ◽  
Author(s):  
Xiaosen Cai ◽  
Binhao Qin ◽  
Yuhang Li ◽  
Qiao Zhang ◽  
Guangxing Yang ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Reduction ◽  
Co Doped

Article

1998 ◽  
Vol 76 (2) ◽  
pp. 228-233
Author(s):  
Kiyohisa Ohta ◽  
Youko Ueda ◽  
Satoshi Nakaguchi ◽  
Takayuki Mizuno
Keyword(s):  
Carbon Dioxide ◽  
Formic Acid ◽  
Maximum Yield ◽  
Practical Interest ◽  
Silicate Rock ◽  
Photocatalytic Reduction ◽  
Photochemical Reduction ◽  
Experimental Conditions ◽  
Illumination Time ◽  
Silicate Rocks

The photocatalytic reduction of CO2 using copper-loaded silicate rocks has been reported. The Cu-silicate rock powders suspended in the solution were illuminated with sunlight. Amphibolite, gneiss, granite, granodiorite, phyllite, quartzdiorite, and shale, which are quite ordinary rocks, were tested as substrates (silicate rock) of the catalyst. These catalysts were specific for the formation of formic acid. The effects of amounts of copper, illumination time, and temperature were investigated on photoreduction of CO2. The 30% Cu-loaded quartzdiorite (0.3 g/g) in these Cu rocks was the best catalyst. The formation of formic acid on the Cu-silicate rock increased with time up to 10 h after which the formation decreased, and then became constant. The formic acid formation decreased with temperature for 10 h sunlight illumination. For the photochemical reduction of CO2, a relatively low temperature was suitable. With photochemical reduction, the maximum yield of formic acid was 54 nmol/g under optimum experimental conditions. The carbon dioxide reduction system developed might well become of practical interest for the photochemical production of raw materials for the photochemical industry.Key words: photocatalytic reduction of carbon dioxide, formic acid, copper-loaded silicate rocks, temperature effect, illumination time.

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