Test Method for Acidity of Benzene, Toluene, Xylenes, Solvent Naphthas, and Similar Industrial Aromatic Hydrocarbons

2004 ◽  
Author(s):  
2017 ◽  
Vol 68 (1) ◽  
pp. 116-120
Author(s):  
Iuliean Vasile Asaftei ◽  
Neculai Catalin Lungu ◽  
Lucian Mihail Birsa ◽  
Ioan Gabriel Sandu ◽  
Laura Gabriela Sarbu ◽  
...  

The conversion of n-heptanes into aromatic hydrocarbons benzene, toluene and xylenes (BTX), by the chromatographic pulse method in the temperature range of 673 - 823K was performed over the HZSM-5 and Ag-HZSM-5 zeolites modified by ion exchange with AgNO3 aqueous solutions. The catalysts, HZSM-5 (SiO2/Al2O3 = 33.9), and Ag-HZSM-5 (Ag1-HZSM-5 wt. % Ag1.02, Ag2-HZSM-5 wt. % Ag 1.62; and Ag3-HZSM-5 wt. % Ag 2.05 having different acid strength distribution exhibit a conversion and a yield of aromatics depending on temperature and metal content. The yield of aromatic hydrocarbons BTX appreciably increased by incorporating silver cations Ag+ into HZSM-5.


In the first paper of this series (Burgoyne 1937) the kinetics of the isothermal oxidation above 400° C of several aromatic hydrocarbons was studied. The present communication extends this work to include the phenomena of ignition in the same temperature range, whilst the corresponding reactions below 400° C form the subject of further investigations now in progress. The hydrocarbons at present under consideration are benzene, toluene, ethylbenzene, n -propylbenzene, o-, m - and p -xylenes and mesitylene.


2001 ◽  
Vol 183 (18) ◽  
pp. 5441-5444 ◽  
Author(s):  
Hikaru Suenaga ◽  
Mariko Mitsuoka ◽  
Yuko Ura ◽  
Takahito Watanabe ◽  
Kensuke Furukawa

ABSTRACT Biphenyl dioxygenase (Bph Dox) catalyzes the initial oxygenation of biphenyl and related compounds. Bph Dox is a multicomponent enzyme in which a large subunit (encoded by the bphA1 gene) is significantly responsible for substrate specificity. By using the process of DNA shuffling of bphA1 of Pseudomonas pseudoalcaligenes KF707 and Burkholderia cepaciaLB400, a number of evolved Bph Dox enzymes were created. Among them, anEscherichia coli clone expressing chimeric Bph Dox exhibited extremely enhanced benzene-, toluene-, and alkylbenzene-degrading abilities. In this evolved BphA1, four amino acids (H255Q, V258I, G268A, and F277Y) were changed from the KF707 enzyme to those of the LB400 enzyme. Subsequent site-directed mutagenesis allowed us to determine the amino acids responsible for the degradation of monocyclic aromatic hydrocarbons.


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