Abstract
Enhancing the intrinsic activity and space time yield of Cu based heterogeneous methanol synthesis catalysts through CO
2
hydrogenation is one of the major topics in CO
2
conversion into ...value-added liquid fuels and chemicals. Here we report inverse ZrO
2
/Cu catalysts with a tunable Zr/Cu ratio have been prepared via an oxalate co-precipitation method, showing excellent performance for CO
2
hydrogenation to methanol. Under optimal condition, the catalyst composed by 10% of ZrO
2
supported over 90% of Cu exhibits the highest mass-specific methanol formation rate of 524 g
MeOH
kg
cat
−1
h
−1
at 220 °C, 3.3 times higher than the activity of traditional Cu/ZrO
2
catalysts (159 g
MeOH
kg
cat
−1
h
−1
). In situ XRD-PDF, XAFS and AP-XPS structural studies reveal that the inverse ZrO
2
/Cu catalysts are composed of islands of partially reduced 1–2 nm amorphous ZrO
2
supported over metallic Cu particles. The ZrO
2
islands are highly active for the CO
2
activation. Meanwhile, an intermediate of formate adsorbed on the Cu at 1350 cm
−1
is discovered by the in situ DRIFTS. This formate intermediate exhibits fast hydrogenation conversion to methoxy. The activation of CO
2
and hydrogenation of all the surface oxygenate intermediates are significantly accelerated over the inverse ZrO
2
/Cu configuration, accounting for the excellent methanol formation activity observed.
Synthesis of methanol from CO2 hydrogenation is a highly attractive route for recycling greenhouse gases to produce clean and value-added fuels and chemicals, simultaneously mitigating the CO2 ...emission and obtaining useful feedstock. Heterogeneous catalysts have been the pillar for CO2 catalytic transformation. The strong metal–support interaction (SMSI) is of great importance for supported catalysts. In addition, the SMSI can be used to enhance the catalytic activity and selectivity to the desired product as well as the stability of the catalysts. Understanding the SMSI is the key to gain deep insights into the structure–activity relationship, which provides valuable guideline for rational design of highly efficient and selective catalysts for methanol synthesis from CO2 hydrogenation. In this review, we present an overview of the advances of CO2 reduction to methanol with focus on catalytic performance, structure characterization, and reaction mechanism for rational design of desired catalysts.
Protic ionic liquids (PILs), such as 1,8‐diazabicyclo5.4.0‐7‐undecenium 2‐methylimidazolide DBUHMIm, can catalyze the reaction of atmospheric CO2 with a broad range of propargylic amines to form the ...corresponding 2‐oxazolidinones. The products are formed in high yields under mild, metal‐free conditions. The cheaper and greener PILs can be easily recycled and reused at least five times without a decrease in the catalytic activity and selectivity. A reaction mechanism was proposed on the basis of a detailed DFT study which indicates that both the cation and anion of the PIL play key synergistic roles in accelerating the reaction.
CO2 capture: Under mild, metal‐free conditions, protic ionic liquids, such as 1,8‐diazabicyclo5.4.0‐7‐undecenium 2‐methylimidazolide DBUHMIm, can catalyze the reaction between CO2 and propargylic amines to form 2‐oxazolidinones. Both the cation and anion of the ionic liquids play key roles in accelerating the reaction.
In this work, we studied the CO2 absorption mechanism by nonaqueous solvent comprising hindered amine 2-(1,1-dimethylethyl)aminoethanol (TBAE) and ethylene glycol (EG). The NMR and FTIR results ...indicated that CO2 reacted with an -OH group of EG rather than the -OH of TBAE by producing hydroxyethyl carbonate species. A possible reaction pathway was suggested, which involves two steps. In the first step, the acid–base reaction between TBAE and EG generated the anion HO-CH2-CH2-O-; in the second step, the O− of HO-CH2-CH2-O− attacked the C atom of CO2, forming carbonate species.
Thermoplastic polyurethane (TPU) films have been widely used as substrates in the rapidly developing fields of flexible electronics and soft actuators. Patterned high-quality cutting is of great ...significance to the promotion of applications. In order to clarify the mechanism of laser cutting, Raman and thermal analyses were performed. Raman tests verified that no new solid by-products were produced after laser cutting. Thermal cracking and thermogravimetric-infrared combined analysis were used to simulate the process of nanosecond laser cutting, and the results showed that the gas by-products released were mainly composed of organic substances including ketone and phenol with benzene ring as the main body, as well as low-chain hydrocarbons and alcohols. Moreover, a cutting quality evaluation standard consists of cutting kerf zone (CKZ) and heat-affected zone (HAZ) was established. And based on this standard, the better nanosecond laser cutting parameters are 10 kHz and 0.03 m/s, which was obtained from a 2-factors and 5 levels orthogonal experiment. Main effect and interaction analysis were performed to clarify the impact of laser parameters on cutting quality and each other.
Recently, deep eutectic solvents (DESs), a new type of solvent, have been studied widely for CO2 capture. In this work, the anion-functionalized deep eutectic solvents composed of phenol-based ionic ...liquids (ILs) and hydrogen bond donors (HBDs) ethylene glycol (EG) or 4-methylimidazole (4CH3-Im) were synthesized for CO2 capture. The phenol-based ILs used in this study were prepared from bio-derived phenols carvacrol (Car) and thymol (Thy). The CO2 absorption capacities of the DESs were determined. The absorption mechanisms by the DESs were also studied using nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), and mass spectroscopy. Interestingly, the results indicated that CO2 reacted with both the phenolic anions and EG, generating the phenol-based carbonates and the EG-based carbonates, when CO2 interacted with the DESs formed by the ILs and EG. However, CO2 only reacted with the phenolic anions when the DESs formed by the ILs and 4CH3-Im. The results indicated that the HBDs impacted greatly on the CO2 absorption mechanism, suggesting the mechanism can be tuned by changing the HBDs, and the different reaction pathways may be due to the steric hinderance differences of the functional groups of the HBDs.
Deep eutectic solvents (DESs) have been widely used to capture CO2 in recent years. Understanding CO2 mechanisms by DESs is crucial to the design of efficient DESs for carbon capture. In this work, ...we studied the CO2 absorption mechanism by DESs based on ethylene glycol (EG) and protic ionic liquid (MEAHIm), formed by monoethanolamine (MEA) with imidazole (Im). The interactions between CO2 and DESs MEAHIm-EG (1:3) are investigated thoroughly by applying 1H and 13 C nuclear magnetic resonance (NMR), 2-D NMR, and Fourier-transform infrared (FTIR) techniques. Surprisingly, the results indicate that CO2 not only binds to the amine group of MEA but also reacts with the deprotonated EG, yielding carbamate and carbonate species, respectively. The reaction mechanism between CO2 and DESs is proposed, which includes two pathways. One pathway is the deprotonation of the MEAH+ cation by the Im− anion, resulting in the formation of neutral molecule MEA, which then reacts with CO2 to form a carbamate species. In the other pathway, EG is deprotonated by the Im−, and then the deprotonated EG, HO-CH2-CH2-O−, binds with CO2 to form a carbonate species. The absorption mechanism found by this work is different from those of other DESs formed by protic ionic liquids and EG, and we believe the new insights into the interactions between CO2 and DESs will be beneficial to the design and applications of DESs for carbon capture in the future.
The contact spacer is the core component of flexible tactile sensors, and the performance of this sensor can be adjusted by adjusting contact spacer micro-hole size. At present, the contact spacer ...was mainly prepared by non-quantifiable processing technology (electrospinning, etc.), which directly leads to unstable performance of tactile sensors. In this paper, ultrathin polyimide (PI) contact spacer was fabricated using nanosecond ultraviolet (UV) laser. The quality evaluation system of laser micro-cutting was established based on roundness, diameter and heat affected zone (HAZ) of the micro-hole. Taking a three factors, five levels orthogonal experiment, the optimum laser cutting process was obtained (pulse repetition frequency 190 kHz, cutting speed 40 mm/s, and RNC 3). With the optimal process parameters, the minimum diameter was 24.3 ± 2.3 μm, and the minimum HAZ was 1.8 ± 1.1 μm. By analyzing the interaction process between nanosecond UV laser and PI film, the heating-carbonization mechanism was determined, and the influence of process parameters on the quality of micro-hole was discussed in detail in combination with this mechanism. It provides a new approach for the quantitative industrial fabrication of contact spacers in tactile sensors.
The mechanism of ultraviolet (UV) nanosecond laser cutting of thermoplastic films and the influence of process parameters on process quality are systematically discussed. The photothermal effect ...plays a dominant role in the interaction between the UV-nanosecond laser and thermoplastic materials. In this photothermal reaction, a heat source with the focal point as the core is formed, around which a thermal carbonization layer, a thermal melting layer, and a thermal expansion layer are formed in order from the inside to the outside. Among them, the thermal carbonization layer is not prevalent, and the thermal melting layer and thermal expansion layer are prevalent. The process quality can be adjusted by adjusting the cutting speed, the laser power, and the repetition number of cuts to regulate the process of heat generation and heat dissipation. In the effective range, the faster the cutting speed and the lower the laser power, the smaller the kerf width and heat-affected zone (HAZ) width. Within a certain range, the depth of kerf can be increased by increasing the repetition number of cuts.
Oil film vortex severely reduces the stability of hydrostatic bearings. A solid-liquid interface with drag and slip properties can weaken the oil film vortex of the bearing. Here, a combined ...picosecond laser ablation and chemical modification method is proposed to prepare surfaces with microbulge array structure on 6061 aluminum alloy substrates. Because of the low surface energy of the perfluorododecyltriethoxysilane modification and the bulge geometry of the microbulge array structure, the surface shows excellent superhydrophobicity. The optimum contact angle in air for water is 164°, and that for oil is 139°. Two surfaces with “lotus-leaf effect” and “rose-petal effect” were obtained by controlling the processing parameters. The drag reduction properties of superhydrophobic surfaces were systematically investigated with slip lengths of 22.26 and 36.25 µm for deionized water and VG5 lubricant, respectively. In addition, the superhydrophobic surface exhibits excellent mechanical durability and thermal stability. The proposed method provides a new idea for vortex suppression in hydrostatic bearings and improves the stability of bearings in high-speed operation.
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