Guaiacol (GUA) is extensively used as the model compound in catalytic studies of lignin, a most abundant renewable aromatic resource in nature. However, GUA is not easy to obtain good activity and selectivity in the hydrodeoxygenation reaction due to its complex structure with various reaction possibilities. So far, researchers have done great efforts to develop efficient catalysts and reaction processes for breakthroughs. This paper reviewed the research progress of transition metal catalysts and noble metal catalysts for hydrodeoxygenation of GUA, and discussed the reaction pathways and the factors which may affect the catalytic behavior, particularly focusing on their catalytic conversions of GUA to phenol or cyclohexanol through CAR-O bond cleavages and aromatic ring saturation. A prospect regarding the future research directions on the catalyst improvement and reaction process optimization were also presented.
Ferric nitrate was used to provide iron source, and Fe?C3N4 composite material was prepared by impregnation method. FT?IR was used to characterize and analyze the prepared materials. The results show that Fe doping does not change the skeleton structure of g?C3N4 and can increase the photocatalytic performance of g?C3N4 materials. Taking orange II as the target pollutant, Fe?C3N4 catalyzed the activation of persulfate to degrade azo dyes under visible light. The effects of persulfate dosage, Fe?C3N4 dosage, pollutant concentration and pH conditions on the degradation effect were examined, and the reaction kinetics was studied to analyze the stability of the prepared catalytic materials. The results show that when the Fe?C3N4 concentration is 2.0 g/L, the molar ratio of persulfate to pollutants is 1 200∶1, and pH=3, the degradation effect is best, and the degradation rate is 77.8%; Fe?C3N4/persulfate system is dual the degradation of nitrogen dyes satisfies the quasi?second?order kinetic equation; Fe?C3N4 material is reusable.
The synthesis method of 2?ethyl?2?aryl?dihydroquinoline derivatives was studied. The synthesis is divided into three steps: the first step, the Suzuki cross?coupling of 2?bromoquinoline and phenylboronic acid; the second step, the exchange of halide lithium; the third step, the nucleophilic addition of the organolithium reagent to the α?position of 2?phenylquinoline to obtain a double?substituted dihydroquinoline derivative. The drug with dihydroquinoline structure was synthesized by this method, and the target product was analyzed by various characterization methods, and the structure of the target product was confirmed.
Oil and gas pipelines (X52 steel) in the marine environment are highly susceptible to corrosion. The effects of different dissolved oxygen concentration, pH, and hydrostatic pressure on the corrosion behavior of X52 pipeline steel in the marine environment was analyzed using electrochemical testing technology and observation of corrosion morphology. The results show that the corrosion of the pipeline slowed down as the ambient pH increased, while the corrosion of the pipeline steel increased as the dissolved oxygen content and hydrostatic pressure increased. The corrosion behavior of pipeline steel under different conditions is controlled by anodic activation of dissolution, and all appear local pitting corrosion phenomenon.
This paper carried out the screening of WO x /SiO2 catalyst carrier and the investigation of WO x loading capacity, and successfully screened a domestic SiO2 carrier with excellent performance. The structure and properties of the catalyst were characterized by nitrogen physical adsorption, XRD, Raman spectroscopy and TEM/EDS. The dispersion of WO x species on the carrier was mainly investigated, the catalytic reaction performance of disproportionation of ethylene and butene to propylene was investigated, and the performance was compared with that of a foreign commercial catalyst. The research results show that the WO x loading threshold of the domestic carrier S?SiO2 is 8%. At this time, the catalyst shows the best catalytic activity and selectivity. Compared with the catalytic performance of the comparative commercial catalyst, the catalyst activity is nearly 10% higher, and the stability and selectivity are equivalent, and the correlation structure characterization results can confirm that the dispersion characteristics of WO x species on the support are the key factors that affect the catalytic performance, while the SiO2 support and loading are both the key to the dispersion state of WO x species. This study can provide a basis for the localization of WO x /SiO2 catalysts for high?efficiency olefin disproportionation reactions, especially the selection of domestic SiO2 carriers.
The cold flow property of biodiesel can be effectively improved by pour point depressants (PPD). The terpolymer (AHM) was prepared by solution polymerization of hexadecyl methacrylate, hydroxyethyl methacrylate and maleic anhydride. The effect of AHM on pour point reduction of biodiesel was also investigated. The hexadecyl methacrylate and AHM were characterized by infrared spectroscopy. The optimal reaction conditions of AHM were determined by single factor experiment: n(hexadecyl methacrylate)/n(hydroxyethyl methacrylate)/n(maleic anhydride)=2∶1∶2, the initiator mass fraction is 3.0%, the solvent mass fraction is 65%, the reaction time is 3 h, and the reaction temperature is 85 ℃. When the mass fraction of AHM is 0.7%, the freezing point of biodiesel decreased by 12 ℃. The morphology of wax crystals precipitated from biodiesel at low temperature after adding pour point depressant was observed by polarizing microscope, and the morphology was more uniform and dense.
The synthesis of gas hydrates with higher saturation under high pressure and low temperature conditions on the seabed was simulated, and use the multi?stage depressurization mode to extract the hydrate as the blank group, and the effects of multi?stage depressurization + alcohol injection, multi?stage depressurization + inorganic salts and chemical agents with different mass concentrations on the decomposition and recovery efficiency of natural gas hydrate were studied. At the same time, according to the experimental results, the chemical agent with the best decomposition efficiency was preferably evaluated. The results show that: the multi?stage depressurization + chemical injection to recover natural gas hydrate can effectively increase the instantaneous gas production rate and improve the overall decomposition efficiency compared with pure depressurization. Among them, the multi?stage depressurization + injection of 30% ethylene glycol has the best performance in alcohols, compared with the pure multi?stage depressurization mode, its decomposition efficiency is increased by 51.3%, and the recovery efficiency within 2 h is increased by 67.3%; the multi?stage depressurization + injection of 15% calcium chloride has the best performance in inorganic salts, compared with the pure multi?stage depressurization mode, its decomposition efficiency is increased by 47.3%, and the recovery efficiency within 2 h is increased by 60.4%. In the actual mining process, the appropriate chemical concentration should be used to avoid environmental pollution.
Understanding the hydrate deposition law can provide ideas for the optimization of intervention operation plans and the prevention and control of hydrate in the wellbore of deepwater gas wells. On the basis of the gas?liquid two?phase flow model, a wellbore pressure and temperature prediction model was developed based on the heat exchange and frictional gradient changes caused by the lowering of the intervention tool, and the temperature and pressure models were coupled to solve by the iterative method. Based on the hydrate growth kinetic model, combined with the wellbore temperature and pressure prediction results, a hydrate deposition model was established, and the hydrate deposition law in the wellbore under intervention operations was analyzed. The results showed that the increase of production led to the increase of pressure difference in the wellbore and the higher wellbore temperature at the mudline under high production. With the release of the intervention tool, the pressure in the wellbore increases, but the pressure increase gradually decreases, and the maximum pressure increase at the wellhead is about 3.0 MPa. When the proportion of the intervention tool diameter is less than 50%, the larger the tool diameter, the higher the wellbore pressure. The location of the wellbore mudline is a high?risk area for hydrate deposition plugging, and the rate of hydrate deposition in low?producing wells is faster than that in high?producing wells. The wellbore hydrate deposition rate is the fastest when the intervention tool is placed near the mudline, and the wellbore hydrate deposition rate is faster when the intervention tool diameter accounts for 50%.
Hydrate formation and deposition in multiphase flows in pipelines can cause flow barriers and affect normal oil and gas production and transportation operations. Based on the characteristics that hydrates are easily formed in water droplets entrained in the gas phase or on the pipe wall in the gas?dominated system of the horizontal annular flow, a hydrate deposition model of the gas?dominated system with different water contents in the pipe wall was established, and the hydrate deposition rule under different influence factors of horizontal annular flow conditions were analyzed. The results show that the hydrate deposition rate increases with the water content and undercooling increased on the pipe wall in the horizontal annular flow. The deposition rate can increase three times of the original one, and the risk of hydrate blockage increases. Hydrate deposition from condensed water increases with time. This study can provide theoretical reference for subsequent related hydrate blockage and hydrate prevention and control, and has important application value.
In the multiphase flow pipeline transportation system， in the process of hydrate slurry flow， rugged terrain will be encountered. At this time， the use of inclined pipeline is particularly important. Therefore， the influence of the flow characteristics of gas hydrate slurry in the inclined pipe on the blocked pipeline was studied. The hydrate plugging experiment of oil + natural gas in oil?based system was carried out on the low?temperature and high?pressure visual hydrate experimental loop， and the effects of initial pressure， initial flow and other factors on the flow and plugging time of natural gas hydrate slurry were explored. At the same time， the micro changes of hydrate particles in the process of hydrate formation， flow and pipe plugging were analyzed by real?time online particle tester. The experimental results show that with the increase of initial pressure， the induction time， formation time and slurry flow time of natural gas hydrate are shortened， and the pipe plugging trend of natural gas hydrate increases. With the increase of initial flow rate， the induction time， formation time and slurry flow time of natural gas hydrate are prolonged， and the pipe plugging trend of natural gas hydrate is reduced. Finally， the process from hydrate formation to pipe plugging and the plugging mechanism were analyzed. The research results of gas hydrate plugging pipelines in oil?based systems show that the probability of gas hydrates blocking pipelines can be effectively reduced by reducing initial pressure and increasing initial flow rates in oil?based systems. The research results can provide theoretical reference and basis for maintaining and ensuring the safe flow of natural gas hydrate in pipelines.
Initial defects and working environment will cause different degrees of cracks on the shaft. In order to analyze the effect of cracks on the rotor system, the finite element models of the cracked rotor were established through Jeffcott rotor dynamics model and fracture mechanics theory. The simulation analysis of different crack depths, crack angles and different speeds was carried out, and then a mechanical comprehensive failure table was used to carry out experimental research on part of the cracked rotors. The results show that: the appearance of cracks causes high?order frequency doubling components such as 2X in the vibration response of the system, and the phenomenon of depressions or even ferrules appeared in the axis track, and the vibration amplitude increases accordingly. As the crack deepens, the instability of the system gradually increases. The change of the crack inclination angle also affects the vibration characteristics of the system, and the 45?degree crack has the greatest impact on the system. When the speed starts to increase, the influence of the cracks on the system gradually decreases, the time?domain waveform tends to be stable, and the axis trajectory gradually changes back to an ellipse. Finally, the experimental results were compared with the simulation data to verify the conclusions of simulation and modeling.
The failure mechanism of pipeline cracking area of ground flare burner was studied. Through the combination of low?power macro analysis, material analysis, microscopic metallographic analysis, scanning electron microscope (SEM) micro morphology and energy spectrum analysis (EDS) and experiment, the causes of pipeline failure and cracking were found out. The sensitive environment (medium), the influence of sensitive materials and stress conditions on pipeline cracking failure were further analyzed. The results show that at a certain temperature, an acidic corrosion environment of H2S+CO2+H2O is formed in the pipeline, and the stainless steel material of the flare burner pipeline is seriously sensitized and has serious intergranular corrosion; Intergranular corrosion causes grain spalling on the surface of pipe wall, resulting in pitting pits, which become the crack source of stress corrosion cracks; The flare burner pipeline will produce a certain degree of stress concentration in the process of manufacturing, processing and device operation. Under the condition of corrosive medium, sensitive material and stress concentration, the flare burner pipeline will fail due to intergranular stress corrosion cracking.
In order to improve the balance between invisibility and robustness of image watermarking, a color image watermarking algorithm is studied by using wavelet transform and Heisenberg array decomposition （HAD） singular value decomposition （SVD）. Firstly, the host image and watermark image are transformed through color space color space, then the host image is transformed by wavelet transform, then the low frequency coefficients are decomposed by HAD and SVD, and the watermark is embedded after SVD in the low frequency. The experimental results show that the proposed watermarking method has strong robustness against multiple watermarking attacks, which is reflected by the normalized correlation NC of the objective evaluation criteria of extracted watermarks. The host image has good invisibility after embedded watermark, which is reflected by objective evaluation standard peak signal?to?noise ratio （PSNR） and structural similarity of images （SSIM）. It can embed grayscale or color large watermark with strong ability of embedding information. It is concluded that that the watermarking method has a certain application value.
A novel distributed model predictive control (DMPC) approach based on immune algorithm (IA) to find out the optimal system decomposition structure is proposed. The IA is used to solve decomposition problems for input clustering decomposition (ICD) and input?output pairing decomposition (IOPD), which can minimize the impact of input?output coupling between systems, and then DMPC algorithm is used to control the decomposed system. This approach effectively reduces the coupling between subsystems, and reduces the communication load of the system. Finally, a heavy oil fractionation chemical process is simulated and compared with the centralized MPC simulation results to verify the effectiveness of the algorithm.
