Direct Synthesis of Dimethyl Ether from Syngas on Bifunctional Hybrid Catalysts Based on Supported H3PW12O40 and Cu-ZnO(Al): Effect of Heteropolyacid Loading on Hybrid Structure and Catalytic Activity

The performance of bifunctional hybrid catalysts based on phosphotungstic acid (H3PW12O40, HPW) supported on TiO2 combined with Cu-ZnO(Al) catalyst in the direct synthesis of dimethyl ether (DME) from syngas has been investigated. We studied the effect of the HPW loading on TiO2 (from 1.4 to 2.7 monolayers) on the dispersion and acid characteristics of the HPW clusters. When the concentration of the heteropoliacid is slightly higher than the monolayer (1.4 monolayers) the acidity of the clusters is perturbed by the surface of titania, while for concentration higher than 1.7 monolayers results in the formation of three-dimensional HPW nanocrystals with acidity similar to the bulk heteropolyacid. Physical hybridization of supported heteropolyacids with the Cu-ZnO(Al) catalyst modifies both the acid characteristics of the supported heteropolyacids and the copper surface area of the Cu-ZnO(Al) catalyst. Hybridization gives rise to a decrease in the copper surface area and the disappearance of the strong acidic sites typical of HPW nanocrystals, showing all hybrids similar acid sites of weak or medium strength. The activity of the hybrids was tested for direct DME synthesis from syngas at 30 bar and 250 °C; only the hybrids with HPW loading higher than 1.4 monolayers showed activity for the direct synthesis of DME, showing that the sample loaded with 2.7 monolayers of heteropolyacid had higher activity than the reference hybrid representative of the most widely applied catalysts based on the combination of Cu-ZnO(Al) with HZSM-5. In spite of the high activity of the hybrids, they show a moderate loss in the DME production with TOS that denotes some kind of deactivation of the acidity function under reaction conditions.

Higher discontinuation rate with a standard-sized compared to a small-sized ‘gold standard’ copper intrauterine device: a case-control review

BackgroundT-shaped intrauterine devices (IUDs) with a copper surface area of 380 mm2 and copper bands on the transverse arms are the most effective types of copper-containing IUDs. A small-sized ‘gold standard’ IUD is available but there has been little research to compare the effects of this small-sized IUD to its standard-sized counterpart.AimTo determine discontinuation rates and reasons for discontinuation at 1 year of the small-sized Mini TT380 Slimline IUD compared with the standard-sized TT380 Slimline.MethodsThe clinical records of women fitted with Mini TT380 Slimline (‘mini’) IUDs were compared with those of women fitted with standard-sized TT380 Slimline (‘standard’) IUDs over a 3-year period (2013–2016).ResultsClinical records were available for 67 women fitted with a mini IUD (mean age 23 years, 64% nulliparous) and 63 women fitted with a standard IUD (mean age 25 years, 39% nulliparous). At 1 year, twice as many standard IUD users (32%, n=20) had discontinued their IUD use compared with mini IUD users (15%, n=10). Complaints of pain and bleeding were more than double (70%, n=14) in those women who discontinued standard IUD use compared with those who discontinued using the mini IUD (30%, n=3). These differences were statistically significant and were unrelated to parity.ConclusionsMore women using a standard-sized ‘gold standard’ IUD rather than its smaller counterpart complained of pain and bleeding, leading to higher discontinuation at 1 year. More research on the association between size and discontinuation of these IUDs is needed.

A study of the risk factors related to ectopic pregnancy in intrauterine device users

Objectives: Analysis of the risk factors related to ectopic pregnancy (EP) among intrauterine device (IUD) users in order to reduce the risk of EP from IUD users and to safeguard women’s health.Methods: A total of 29 EP cases were collected and 1:1 matched controls in IUD users by case-control study.Results: The data showed that pregnancies had significant association with EP, two pregnancies and three or more pregnancies were increased the risk of EP, adjusted odds ratio AOR = 14.39, 95% CI: 2.37, 87.49 and AOR = 14.87, 95% CI: 2.27, 97.38 respectively. The risk of EP in women of previous abdominal or pelvic surgery was also significantly increased (AOR = 4.43, 95% CI: 1.04, 18.92). While no significant association have been seen with age, first or second time use IUD, periods of insertion, types of IUD, and copper surface area of IUD.Conclusion: The results suggest that the number of pregnancies significantly increase the risk of EP, there is no significant association between the risk of EP and copper surface area or shape of IUD used. Therefore, a woman’s individual risk factors will lead to a rise in the risk of EP, there is a need to the suitability of her contraceptive. It is beneficial to reduce the risk of EP by the prevention of unwilling pregnancy and induced abortion.

Performance of Cu-Based Catalysts in Low-Temperature Methanol Synthesis

The reactions of the methanol synthesis were conducted from the CO/CO2/H2 on the Cu-based catalysts using different solvent at 443 K and 3.0 MPa. The alcohol solvent had the activity in the low-temperature methanol synthesis reaction. The activity of the Cu-based catalyst with ZnO as carrier was higher than that of the catalyst with CeO2, Al2O3, or TiO2 as carrier separately in the reaction. The addition of the CeO2 to the Cu/ZnO catalysts improved the copper species dispersion, so that it was easier for the reduction of the Cu/CeO2-ZnO catalyst than that of the Cu/ZnO catalyst according to the TPR analysis. The variation trend of the BET surface area and the copper surface area was consistent with those of the activity for the Cu/ZnO and the Cu/CeO2-ZnO catalysts in the reaction. The activity of the Cu/CeO2-ZnO catalyst was higher than that of the Cu/ZnO catalyst in the reaction.