Vapour phase catalytic transformations of terpene hydrocarbons in the C10H16 series. III. Dehydrogenation of Δ3-carene over modified chromia and chromia–alumina catalysts

1976 ◽  
Vol 54 (21) ◽  
pp. 3458-3463 ◽  
Author(s):  
V. Krishnasamy ◽  
L. M. Yeddanapalli
Keyword(s):  
Hydrofluoric Acid ◽  
Vapour Phase ◽  
Potassium Ions ◽  
Total Conversion ◽  
Fluoride Ions ◽  
Catalytic Transformations ◽  
Alumina Catalysts

The vapour phase dehydrogenation of 3-carene has been studied over chromia, chromia–alumina, chromia doped with potassium, and chromia–alumina doped with potassium and fluoride ions. Addition of potassium to chromia and chromia–alumina up to 1% by weight does not significantly affect the overall conversion of 3-carene whereas it increases its dehydrogenation to p- and m-cymenes. Potassium ions above 1% lower both the total conversion and dehydrogenation of 3-carene to cymenes. The ratio of p- to m-cymene over chromia–alumina is enhanced by added potassium ions up to 2%, but over chromia it remains unaffected. Addition of potassium to chromia decreases the formation of menthanes and menthadienes but its addition to chromia–alumina reduces the formation of menthanes and increases that of menthadienes. Impregnation of chromia–alumina with hydrofluoric acid suppresses the formation of menthadienes and increases that of menthanes. All these are explained in terms of the effect of added potassium and fluoride ions on the acidity of the catalysts.

scholarly journals Vapour phase catalytic transformations of terpene hydrocarbons in the C10H16 series. IV. Effect of nitrogen, hydrogen, and pyridine on the dehydrogenation of Δ3-carene over chromia and chromia-alumina catalysts

1977 ◽  
Vol 55 (16) ◽  
pp. 3046-3049 ◽  
Author(s):  
V. Krishnasamy ◽  
L. M. Yeddanapalli
Keyword(s):  
Partial Pressure ◽  
Vapour Phase ◽  
Catalytic Transformations ◽  
Partial Pressures ◽  
Alumina Catalysts ◽  
Catalyst Surfaces

The influences of nitrogen, hydrogen, and pyridine on the conversion of 3-carene into various products over chromia catalyst at 450 °C and over chromia–alumina at 400 °C have been investigated. Nitrogen acts as a diluent over these catalysts; hydrogen at low partial pressures enhances the formation of cymenes over chromia, but suppresses its formation over chromia–alumina. Increase of the partial pressure of hydrogen increases the proportion of men thanes over chromia–alumina, but decreases it over chromia catalyst. Pyridine suppresses the over-all conversion of 3-carene and the formation of cymenes over chromia and chromia–alumina; however, it increases the formation of menthadienes over chromia–alumina. These observations are explained in terms of the acidity of chromia and chromia–alumina, the diluting effects of nitrogen, hydrogen, and pyridine, and their ability to adsorb and desorb over the catalyst surfaces.

Dehydrogenation of 3-carene in the vapour phase. II. Performance studies of chromia and chromia-alumina catalysts

1980 ◽  
Vol 33 (6) ◽  
pp. 1313 ◽  
Author(s):  
V Krishnasamy
Keyword(s):  
Water Vapour ◽  
Performance Studies ◽  
Active Sites ◽  
Vapour Phase ◽  
Progressive Increase ◽  
Oxidation States ◽  
Side Reactions ◽  
Potassium Ions ◽  
Alumina Catalyst ◽  
Alumina Catalysts

The influence of contact time on the dehydrogenation of 3-carene over reduced chromia and chromia-alumina catalysts has been investigated at 450 and 400°C respectively. For the dehydrogenation, reduced chromia- alumina catalyst is more active than reduced chromia alone. It has been found that the dehydrogenating ability of reduced chromia is superior to that of oxidized chromia. The effect of water vapour on reduced chromia showed an initial suppression of its reactivity, but at intermediate values increased its activity. Progressive increase of water vapour was seen to modify the active sites of reduced chromia, an effect similar to that of the oxidized sample. ��� The dehydrogenation of 3-carene, over chromia, follows second-order kinetics. The energy of activation is found to be greater for oxidized than for reduced chromia. Impregnation of chromia with potassium decreases the activation energy of reduced chromia and enhances its dehydrogenation ability by suppressing the side reactions. ��� The observed experimental data are explained in terms of the acidity of the catalysts, oxidation states of chromium ions and the promoting influence of potassium ions.

Critical care management of hydrofluoric acid burns with a negative outcome

2021 ◽  
Vol 14 (6) ◽  
pp. e242187
Author(s):  
Aalekh Prasad ◽  
Heba Ibrahim ◽  
Katherine Mortimore ◽  
Rohan Vandabona
Keyword(s):  
Hydrofluoric Acid ◽  
Care Management ◽  
Vital Role ◽  
Severe Metabolic Acidosis ◽  
Fluoride Ions ◽  
Subcutaneous Injections ◽  
Electrolyte Disturbances ◽  
Severe Burns ◽  
Systemic Reactions ◽  
Critical Care Management

Hydrofluoric acid is a highly corrosive acid widely used in various industries. When in contact with skin it causes local and systemic reactions due to the generation of fluoride ions. Severe burns are associated with high mortality rates, approaching 100%. We present a 21-year-old man with 15% full thickness burns, severe metabolic acidosis, hypoxia and electrolyte disturbances. The burns were treated with topical and subcutaneous injections of calcium gluconate, and the patient was given intravenous fluid, calcium chloride, magnesium and insulin-glucose infusions. Continuous renal replacement therapy was initiated due to the severity of the systemic toxicity. Extracorporeal membrane oxygenation was considered as it plays a vital role when conventional therapies fail. Our patient suffered multiple cardiac arrests and cardiopulmonary resuscitation was conducted several times but despite extensive efforts, he did not survive.

Effect of Artificial Saliva with Fluoride Ions on the Color of Ti-Porcelain

2010 ◽  
Vol 105-106 ◽  
pp. 572-575
Author(s):  
Hai Tao Wu ◽  
Hai Yan Shang ◽  
Li Tong Guo ◽  
Jian Feng Yang ◽  
Tian Wen Guo
Keyword(s):  
Hydrofluoric Acid ◽  
Oral Fluid ◽  
Ph Value ◽  
Artificial Saliva ◽  
Fluoride Ions ◽  
B Values ◽  
Color Changes ◽  
Lack Of Information ◽  
Color Data ◽  
Opaque Body

In the acidic oral environments containing fluoride ions, hydrofluoric acid (HF) would form and affect the color of Titanium porcelain crown, but there is a lack of information on how color is affected by this oral fluid. The purpose of this study was to investigate the effects of various artificial saliva simulating oral environments in the presence of fluoride ions with different pH value on the color of self-made dental opaque, body porcelain, belonging to the Na2O-K2O–MgO–CaO–Al2O3–SiO2 glass system. Disc-shaped specimens, 5 mm diameter and a 2-mm thickness, were made by firing. Specimens were immersed in artificial saliva in the presence of fluoride ions with different pH value for 7, 14, 21 days, and then the color of the specimens was compared with the color of the initial specimen. The interactions were present in L*a*b* values between pH value and the day of immersion. The changes in L*a*b* color data as the day of immersion and pH value increased were revealed, which can resulted in perceptual color changes in L*a*b* color parameters.

Vapor Phase Catalytic Transformations of Terpene Hydrocarbons in the C10H16 Series. II. Aromatization of α-Pinene over Chromia–Alumina

1972 ◽  
Vol 50 (1) ◽  
pp. 113-118 ◽  
Author(s):  
A. Stanislaus ◽  
L. M. Yeddanapalli
Keyword(s):  
Vapor Phase ◽  
Alumina Support ◽  
Pure Alumina ◽  
Catalytic Transformations ◽  
Alumina Catalysts

The aromatization of α-pinene in the vapor phase over chromia gel and chromia–alumina catalysts prepared from aluminas of different acidity has been studied. The acidity of alumina support has a remarkable influence on the composition of the aromatics resulting from the dehydrogenation of α-pinene. Over weakly acidic chromia–alumina doped with 1% sodium catalyst, α-pinene is aromatized to p-cymene, 1,2,4- and 1,2,3-trimethylbenzenes with traces of toluene and xylenes, whereas over the strongly acidic chromia – pure alumina and chromia–alumina containing 5% HF catalysts it gives considerable amount of m-cymene, toluene, and tetramethylbenzenes. A satisfactory mechanism to explain the formation of these compounds is offered.

Effects of Ion Stress on the Oxidation Activity of Acidithiobacillus ferrooxidans

2015 ◽  
Vol 1130 ◽  
pp. 165-168
Author(s):  
Ying Bo Dong ◽  
Hai Lin
Keyword(s):  
Acidithiobacillus Ferrooxidans ◽  
Metal Ion ◽  
Potassium Ions ◽  
Trivalent Metal ◽  
Fluoride Ions ◽  
Oxidation Activity ◽  
Inhibition Effect ◽  
Potassium Magnesium

The effects of stresses induced by four ions (potassium, magnesium, aluminum and fluoride ions) on the growth and activity ofAcidthiobacillus ferrooxidansLD-1 (At.fLD-1) were investigated. The results showed that these four ions inhibited the growth and activity ofAt.fLD-1 to different extents. The inhibition effect of these four ion stresses followed the order potassium < magnesium < aluminum < fluoride. The inhibition effects of the trivalent metal ion (aluminum) are greater than divalent (magnesium) and monovalent (potassium) ions at the same concentrations. The inhibition of cations onAt.fLD-1 was stronger than that of anions.

STUDIES ON THE CYTOGENETIC AND GENETIC EFFECTS OF FLUORIDE ON BARLEY.: I. A COMPARATIVE STUDY OF THE EFFECTS OF SODIUM FLUORIDE AND HYDROFLUORIC ACID ON SEEDLING ROOT TIPS

1973 ◽  
Vol 15 (4) ◽  
pp. 695-702 ◽  
Author(s):  
S. S. Bale ◽  
G. E. Hart
Keyword(s):  
Comparative Study ◽  
Seedling Growth ◽  
Sodium Fluoride ◽  
Chromosomal Aberrations ◽  
Hydrofluoric Acid ◽  
Root Tips ◽  
Fluoride Ions ◽  
Binucleate Cells ◽  
Seedling Root ◽  
Inhibition Of Growth

The effects of sodium fluoride and hydrofluoric acid on barley were determined and compared following treatments of seedling root tips at three different concentrations (1 × 10−2M, 1 × 10−4M, 1 × 10−6M) and for six different durations (12, 24, 36, 48, 60, and 72 hr). Treatment with a 1 × 10−2M concentration of either sodium fluoride or hydrofluoric acid markedly slowed the rate of seedling growth. However, no inhibition of growth was observed following treatment with a 1 × −4M or a 1 × 10−6M concentration of either agent. Chromosomal aberrations were induced and mitosis was inhibited by each of the three different concentrations of both sodium fluoride and hydrofluoric acid. The sodium fluoride treatments induced a higher frequency of chromosomal aberrations than did the hydrofluoric acid treatments, possibly due to differences in pH and in the total available fluoride ions. These treatments produced bridges, fragments, chromosome gaps, binucleate cells and micronuclei.

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