No, you must not use 2-pole circuit breaker as 1-pole circuit breaker (series connection as only single phase ). If using it as 1-pole circuit breaker, these two things must be considered as below.
1. If using 2-pole MCCB as 1-pole circuit breaker, it will not trip or operating time will be longer when carrying 130% of the rated current. (The operation at 130% is not guaranteed.) The standard does not mention about assurance of tripping performance at 130% with 2-pole and 3-pole circuit breaker, and also the operation check of carrying 130% of the rated current to 1-pole is not carried out before delivering. However, it is no problem for time-delay tripping of 200% or more of the rated current and switching current of the rated current or less with 1-pole. (Applicable circuit voltage is same as below 2)
2. If using 2-pole MCCB as 1-pole circuit breaker, 1-pole breaking performance when considering ground fault is as below.
* When the rated breaking capacity as 2-pole type exceeds AC5000A, 1-pole breaking capacity is AC5000A. When the rated voltage exceeds AC240V, 1-pole breaking performance (applicable voltage) is up to AC240V.