Production of phenols from lignin was investigated using a new conversion process consisting of two reaction steps. In the first step, depolymerization of lignin was carried out in an autoclave ...reactor using a silica-alumina catalyst in a water/1-butanol solution. The yield of lignin-derived liquid product reached 85–88C-mol% under the appropriate reaction conditions. In the second step, catalytic cracking of the liquid products from the first step was carried out using a fixed‐bed flow reactor over an iron oxide catalyst. With this method, total recovered fraction of phenols and the conversion of methoxy phenol reached 6.6–8.6% and 92–94%, respectively.
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► Production of phenols from lignin was investigated via a two-step process. ► Depolymerization of lignin over silica-alumina was promoted using a H2O/BuOH solution. ► Reaction of the lignin-derived liquid product was carried out over an iron oxide catalyst. ► The iron oxide catalyst successfully converted phenols into phenol and cresol.
Cu-based spinel-oxides CuB2O4 (B = Fe, Mn, Cr, Ga, Al, or Fe0.75Mn0.25) were synthesized via a sol-gel method and subsequent solid-state reaction. The spinels mechanically mixed with gamma-Al2O3 were ...evaluated for production of hydrogen from dimethyl ether steam reforming (DME SR). The reduction behavior and crystal property of these spinel-oxides, and the Cu oxidation state in spinel catalysts were investigated by temperature-programmed reduction, X-ray diffraction, and X-ray photoelectron spectroscopy techniques. The reduced phases of the Cu-based spinel catalysts that strongly affected the catalytic activity and durability were composed of metallic copper with metal oxides (MnO (B = Mn), Cr2O3 (B = Cr), and Al2O3 (B = Al)) or with spinels (CuGa2O4 (B = Ga), Fe3O4 (B = Fe), and MnFe2O4 (B = Fe0.75Mn0.25). The stability of B metal oxides and the interaction between copper species and B metal oxides significantly contributed to the reforming performance.
The durability of composite catalysts of CuFe
2O
4 and
γ-Al
2O
3 was investigated during steam reforming (SR) of dimethyl ether (DME). Partial degradation of the composites proceeded due to the ...concomitant effect of copper sintering and carbon formation. The catalyst degraded after SR for 1100 h was regenerated by calcination in air in the temperature range of 500–700 °C; redispersion of copper via spinel formation and simultaneous carbon burning were achieved. The apparent activation energy for DME SR over the catalyst was estimated to be in the range of 150–160 kJ mol
−1 and remained almost stable during the DME SR reaction test for 1100 h. Degradation of the catalyst was found to follow first-order kinetics with a deactivation rate constant of
0.95
×
10
−3
h
−1
.
The catalytic performances of solid acids (Al
2O
3 derived from bayerite (PBT), γ-Al
2O
3 (ALO8), ZSM-5, H-mordenite, and TiO
2) in hydrolysis of dimethyl ether (DME) to methanol have been ...investigated. The stronger and the larger acid sites give rise to higher conversion in hydrolysis; however, fast degradation due to coking and low quality of product are observed. The acid strength of the solid acids is as follows: H-mordenite
>
ZSM-5
>
PBT, ALO8
>
TiO
2. The apparent activation energies of DME hydrolysis over H-mordenite, ZSM-5, PBT, ALO8, and TiO
2 were determined as 73, 76, 101, 146, and 186
kJ
mol
−1, respectively. Next, steam reforming of dimethyl ether over composites of the solid acid and copper iron spinel was evaluated for hydrogen production. The composites of alumina and Cu spinel are active and durable to produce H
2-rich reformate with CO
2 as the major products along with trace amounts of CO. The Cu content of 13.3–17.7
wt% in the composites was optimum in terms of reforming performance. Alumina–spinel composites are superior to zeolite–spinel ones with regard to stability. Increasing the steam-to-carbon ratio obviously suppresses the catalyst degradation.
The performance of solid acids in hydrolysis of dimethyl ether (DME) strongly depends on the acid properties. The activation energies of DME hydrolysis over H-mordenite, ZSM-5, Al
2O
3 derived from bayerite (PBT), γ-Al
2O
3 (ALO8), and TiO
2 were determined by Arrhenius plots. The composites of alumina and Cu spinel are superior to those of zeolite and Cu spinel with regard to stability in steam reforming of dimethyl ether.
▪
A simple thermal treatment remarkably enhances the activity and durability of CuFe2O4–Al2O3 composite catalysts in reforming dimethyl ether for hydrogen production. The most effective treatment ...temperature range is 700 to 800 °C. The active phase, CuFe1.5Al0.5O4 formed through a solid‐state reaction between CuFe2O4 and Al2O3, and the original phase, CuFe2O4, contribute synergistically to the enhancement.
Effects of Ni doping on the catalytic behavior of Cu x Ni1−x Fe2O4 (x = 1, 0.95, 0.90, 0.50) mixed with Al2O3 were investigated in steam reforming of dimethyl ether for hydrogen production. The ...stability of the catalyst was significantly enhanced by doping Ni species to CuFe2O4. Formation of CuNi alloy was confirmed as the amount of Ni addition increased. The suppression of the sintering rate was clearly evidenced over Ni-doped catalysts as compared with the undoped one, while the effect on carbon deposition rate was unclear. Nevertheless, an increasing amount of Ni dopant to Cu−Fe spinel retarded the conversion of dimethyl ether and led to high selectivity to CH4 and CO.
Influences of solid–acid catalyst on dimethyl ether steam reforming (DME SR) and DME hydrolysis for hydrogen production were investigated. Series of zeolite (JRC-ZHM20(5), JRC-ZHM90(1) as H-mordenite ...type and JRC-Z5-90H(1) as ZSM-5 type) and of alumina (ALO8, TA1301, TA3301, DK503, NKHD24, NKHO24 and NK324) were used as acidic catalysts for DME hydrolysis. The composite catalysts of the acidic catalyst and CuFe
2O
4 spinel catalyst were employed for DME SR. DME SR activity strongly depended on the acidic catalyst that is active for DME hydrolysis. The hydrolysis of DME, the rate-determining step in DME SR, is equilibrium-controlled. Zeolite exhibited high activity for DME SR at a low temperature range of 200–275
°C, since the hydrolysis could effectively proceed over strong BrØnsted acid-sites approaching its equilibrium. Alumina possessing Lewis acid-sites was active for DME hydrolysis in the higher temperature range from 275 to 450
°C. CO
2 and CO with relatively small amounts of CH
4 were found as primary carbon-containing compounds when alumina was used as the acidic catalyst. In the case of zeolite, besides those carbon compounds, C
3H
8,
i-C
4H
10, and
n-C
4H
10 were detected during SR and hydrolysis of DME. It was found that not only the acid amount of the acidic catalysts, but also the acid strength and the type of acid-site definitely affected the steam reforming and hydrolysis activity. γ-Alumina (ALO8) mixed with CuFe
2O
4 exhibited the highest DME conversion and hydrogen production with optimum reforming temperature at 350–375
°C. Stable activity for DME hydrolysis was attained over ALO8 with high durability for 25
h.
I improved the CPU simulator so that it can be used with Excel online. In the previous simulator, the simulation was performed by using a VBA program. However, some students could not use the ...simulator because they could not use Excel due to differences in operating systems. Therefore, in order to make the simulator available to all students, the simulation is performed using Excel Online. However, VBA programs are not available in Excel Online. Therefore, I improved the CPU simulator so that it can be simulated using only cell functions. In the new simulator, repetitive structures are expanded and expressed as a program without repetitive structures. In this paper, I report on the CPU simulator realized with only cell functions.
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