The initial atmospheric corrosion of zinc induced by formic acid, acetic acid, and propionic acid has been followed in situ with infrared reflection absorption spectroscopy ͑IRAS͒. An optical model was applied to quantify the IRAS data, which enabled the absolute amounts of the two main species detected, ZnO and zinc carboxylate ͑mainly hydrated or hydroxyl zinc carboxylate͒, to be derived. The formation rate of zinc carboxylate increases as propionic Ͻ acetic Ͻ formic acid and is mainly governed by the deposition velocity of each acid into the existing aqueous adlayer. The formation rate of ZnO and the overall corrosion rate of zinc increase in the order formic Ͻ acetic Ͻ propionic acid and are mainly attributed to the expected pH of the aqueous adlayer. The corrosion rates deduced are at least 1 order of magnitude higher than the experimentally determined field data due to a higher organic acid concentration used herein ͑120 ppb͒ and a higher average relative humidity ͑90%͒.
Pipelines play an important role in the national/international transportation of natural gas, petroleum products, and other energy resources. Pipelines are set up in different environments and consequently suffer various damage challenges, such as environmental electrochemical reaction, welding defects, and external force damage, etc. Defects like metal loss, pitting, and cracks destroy the pipeline’s integrity and cause serious safety issues. This should be prevented before it occurs to ensure the safe operation of the pipeline. In recent years, different non-destructive testing (NDT) methods have been developed for in-line pipeline inspection. These are magnetic flux leakage (MFL) testing, ultrasonic testing (UT), electromagnetic acoustic technology (EMAT), eddy current testing (EC). Single modality or different kinds of integrated NDT system named Pipeline Inspection Gauge (PIG) or un-piggable robotic inspection systems have been developed. Moreover, data management in conjunction with historic data for condition-based pipeline maintenance becomes important as well. In this study, various inspection methods in association with non-destructive testing are investigated. The state of the art of PIGs, un-piggable robots, as well as instrumental applications, are systematically compared. Furthermore, data models and management are utilized for defect quantification, classification, failure prediction and maintenance. Finally, the challenges, problems, and development trends of pipeline inspection as well as data management are derived and discussed.
MIL-100(Cr)
was synthesized and evacuated under different temperatures
to generate a series of heterogeneous catalysts for ethylene oligomerization.
These catalysts showed moderate catalytic activities for ethylene
oligomerization but high selectivities to low carbon olefins C6, C8,
and C10. Moreover, the oligomer distribution was different depending
on the evacuation temperature. The XPS results showed the reduction
of some CrIII active sites in the MIL-100(Cr) structure
to CrII active sites, which made the catalysts show polymerization
activities. The MIL-100(Cr)-250 catalyst evacuated at 250 °C
exhibited the highest oligomerization and polymerization activities
up to 9.27 × 105 g/(molCr·h) and 0.99 ×
105 g/(molCr·h) respectively. The oligomerization
selectivity to low carbon olefins C6, C8, and C10 was about 99%. The
byproduct polymer from MIL-100(Cr)-250 belonged to linear polyethylene
with ultrahigh molecular weight and broad molecular weight distributions.
This work demonstrated that MOFs containing coordinatively unsaturated
metal sites might be a promising selective catalyst for ethylene slurry
oligomerization.
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